First time off roader. Need help deciding on a small bore 2 stroke for mostly trail riding - YZ125X/125XC/150XC-W/ etc.

You can have fun on a 125 at that size. I would probably lean towards a 150 or yz250x

Torque is the key to trails. The 250 you think maybe too much is actually easier to ride than a 125. 150>125 because of torque. 200cc bikes were a nice sweet spot 

^^ this.  A YZ 250x or KTM 300 set up to chug around will be way easier and fun to ride than a smaller bore you’re trying to coax all the power out of just to get up a hill or finesse your way through some technical stuff. Good luck, have fun and remember traction isn’t going to be what your used to on your street bikes. 

Great advice above. A properly set up 250 or 300 is a much better and easier bike to ride in the woods. I've owned a 250X and a few 250XCW's. Currently have a 125X and a TE-300. The 250's and 300 each have enough torque to ride a gear high and lug around the trails. The 125, not so much. Although fun, the 125X requires a great deal more conditioning and aggression to ride at the same pace as a 250 or 300. Is the KTM/TPI worth the extra 3-4k? Kind of relative really. If you can afford it and don't know much about jetting, probably so. The newer gen KTM's are great bikes and much more refined than the YZ or older gen KTM's. If KTM/Husky is what you decide on, I'd stick with a 2017 or newer model. 

“First time offroader” and 300 shouldn’t even be in the same conversation. 300s seem great when you hop on them and lug around, but once you start getting tired and making mistakes, that’s when the issues arise for someone with lesser experience. Also, if you’re wanting to learn actual riding skills, a 300 isn’t going to be the best route for that (or even a 250, for that matter). 

It’s also hard to get good feedback when you’re getting opinions from varying skill levels, or people who ride completely different terrain and different elevations from what you have in your area. Your profile says you’re in AR. Most of the stuff I’ve ridden in AR was at least fairly tight, and a small bore would do well there. Look into the YZ125X, various Austrian offroad 125/150s, and the Beta 200. 

125's are a riot but really not great for someone new too trail riding.  The lack of torque means you really need to keep it on the pipe or you're not making it up hills.  I would go for a 250 tpi bike. They have super smooth bottom end and tons of torque and really are quite easy to ride.  I had a 300 and it was an amazing bike that I even let several newer riders try out and they all were amazed how much easier it was to ride in technical terrain and on hills because of the smooth power delivery and almost unkillable torque.  The YZ is a cheaper option but way more vibration and the motor is far closer to an MX bike than a woods bike. The new TBI bikes are supposedly similar on the bottom end power but have the big punch on top. I just got one but haven't been able to really ride it just yet.  The TPI bikes though are dropping in price and there are a lot for sale right now as everyone jumps to the new gen bike.

A 250 4 stroke is probably your best bet (YZ250FX..) but if you want a 2 stroke then get a YZ250x. As others have said, 125s will be a challenge as soon as you get into any hills, they are a blast to ride but can be difficult cause there’s no real power if you’re not riding aggressively/in the right gear. Although, if you really want to learn fast and have the determination to deal with some frustration at first, a small bore will definitely teach you well. 

Another thing, once you ride for a few months you’re gonna know what YOU really want. All the advice in the world just gets you started, once you ride for a while and see what you’re strengths and weaknesses are you’ll know what direction to go.

Do you have any buddies who ride off-road? See if they'll let you ride one of their bikes so you can compare. I'm leaning toward recommending a 250 also, but make sure you get an "X" model with the mellower gearing and tune. An MX version might be a little too pipey for your purposes. 

Look into a 200 whether it be a ktm or beta. Best of both worlds. Plenty of torque and nimble in the woods. I have a 2015 200xcw and everyone who rides it is blown away.

Beta 200

Beta 200RR

Jason Raines is bringing the fleet of Yamaha dirt bikes to WW Ranch January 21-22 for demo rides. Not sure if that is too far for you but what better reason for a road trip? Even if it costs a few hundred bucks it's worth it to know you are getting a bike that works for you. 

Yamaha Events (yamahamotorsports.com)

Current Models Available:

TT-R 50E, TT-R 110E, YZ65, YZ85, YZ85LW, YZ125, YZ125X, YZ250, YZ250F, YZ250FX, YZ450F, YZ450FX

Lots of different opinions. I'm with falcon on seeing if you can test ride some buddies bikes first. My opinion is still a 125 might be good for the first couple rides, but you ride street bikes so you know how brakes and a clutch work, you don't have to turn the throttle all the way open, get something torquey that lugs and chugs. IMO you want at least 1 cc of displacement per each 1 lb of body weight    Try to get some test rides if you have the means 

Given your weight I would not get any 125. The TPI 150 W and TE 150 could work but honestly I would look at a Beta 200 or the X Trainer. I know the X-Trainer is a 300 but its a mild one. Its less expensive, has a lower seat height and the suspension is going to be set better for you. At 190 you may need different springs, at 200 for sure you will. That's on all those bikes.

You said…

“I wanted to grab a dirt bike to learn and have fun on trails (might go on a track a couple times but not to race or anything).”

The perfect solution has already been made and, yes, I’ve ridden it “at the track” and it’s A BLAST!

The Husky TE150

The Husky 150 is a lot like Kawasaki’s good’ol KDX 200: It’s got good torque & more USABLE power than you’d expect from “a little 150”. It’s soooo much fun on the trail. 

First off whats the price range?  If we are talking new bikes, I think you would be fine on a 125 or 150, if low end torque is an issue in order to get up a steep hill then you should probably look at a four stroke. 

Husky or KTM 150 tpi for learning to trail ride. The Beta 200 has similar power so it should also be good. If you don't have steep hills a 125 would be ok too. A 250f can be ok depending on the model, but they stall a lot easier than a 2 stroke which will lead to some tip overs and frustration if you are riding in anything very technical.

If you're willing to go used, a Kawasaki KDX 200 (or 220) is still a solid starter bike.  The 95-06 is a little easier to find parts for, but the 89-94 still has all of the basics covered.  It has a nice, usable, powerband.

It still fits my 6'4" 275lb. frame pretty well.  Mine (a 1990) is stock aside from a jetting/suspension spring change and was bone stock when I acquired it from my uncle a few years back.  He ran it in OE configuration for nearly 20 years.

You know, that REALLY is a good way to go. We have a coupl'a those around my riding group...I get on one every now and then to remind me of one of my favorite bikes...EVER...

My White on Blue '91 KDX200: Raced and Won everything from MX to ISDE Quali's on that bike!

We've got an '04 and '05 in our group. The '05 220 is pretty darn torquey.

Xr400 or Wr250f

Add any year KTM 200 to the KDX “legendary” woods bike list

It is a great bike but if you go the 150 route make sure you get a TPI unit. It has a lot more bottom end than the carb. 

Kudos to you guys for actually answering this cat’s question.  And not one vitard suggested a cr500.  Maybe we’re not all doomed after all.

I have a 2005 KTM 200EXC and I’ve ridden the 2012 or 13 200XC. Both are great bikes. As many have said above, 125s need to be ridden hard. My brother had the 150 carb model and said it was okay but not as good as the ktm 200 engine. I would highly recommend looking for a used one. 
 

I also love the KDX220. Not quite as sexy or refined as a KTM but they are great bikes and perfect for beginners. 
 

I would be interested with trying a Beta 200 but I’ve never ridden any of them. My friend has the four stroke (440 if I remember correctly) and he said when it runs it’s great, but he’s had electrical issues that he’s been chasing around for a year and can’t figure out. I would think a 2 stroke would be much simpler though and probably wouldn’t have many issues. 
 

Good luck and keep us posted with what you decide on. 

I weight 190-200 my 150 lugs me around all day. Plenty of chugging power actually very hard to stall. It will rip or chug and it is so compact and lightweight. It rewards aggressive riding but doesn’t require it

Beta 200. Hands down.

I started out on a 250 and it WILL be easier to ride on trails and track but I wish I would have started on a 125.  MANY skills to be learned on a 125.

Yep, Beta 200 would be first choice.  I also would take a close look at the Rieju MR200 Racing.