is 4 or two stroke better for a suzuki rm

2 strioke= less maintnance more clutch use and more fun more speed
4 stroke more maintnance more power longer lasting

4 strokes are not longer lasting. The maintenance period for a 125 2 stroke is the same for a 250 4 stroke, but the 4 stroke will cost you 3 times as much typically. Performance add-on parts are also much more expensive for a 4 stroke. Just look at aftermarket pipes and you'll see what I mean.

The resale value is also better for 2 strokes currently, mostly because how cheap they are to rebuild and the lesser chance of catastrophic damage due to less moving parts (no cam, valves, lifters, springs, cam-chain, oil pump, fuel pump, etc.). You'll ride longer with more money on your pocket with a 2 stroke, and become a better rider, but you'll be faster on a 4 stroke, usually, because they are easier to ride and you have a CC advantage.

Why not a 250cc 2 stroke? Are you a beginner moving up from any particular size? Maybe a KTM 150sx (powerband plus chuggin power)??

If you are buying a used 250 4-stroke, you are asking for a lot of trouble. Unless the bike was maintained in super condition the 125 will make for a lot less headaches.

oh and they don't make a 125 4 stroke.