Who had the best looking bike of all time?

Yeah classics will always be classics, factory 2000s 250 two strokes were the coolest of all time, and looks like Reedy wins the OP’s original question, with at least three nominations and lots of thumbs up.

If success is tested by visceral reactions, maybe that an entire generation of current and future racers were sporting chubbies when this bike was intro'd gives it the title:

And then there was the best, and this might have been the best of the best:

Simple yet, very well refined. 

WARNING: Moto Porn Ahead

Probably my favorite to date. I’m not really into the overdone graphics these days. Once again, simple yet, clean. 

This beautiful thing right here!
 

whoever has that 2024 retro KX450. and not because of the retro graphics. the lack of stock graphics let’s brilliant contours of that bikes shine through. aside from the 2011 KTM is the finest dirtbike ever made.

actually after seeing the the works HRC RC’s above I changed my mind. I mean, just wow.

Well for me the best looking bike has the best shape, most noteably the front fender. If you have a great looking bike, but the front fender is sticking up like a big pelican beak, then it looks stupid.

The Hondas from ‘85 to 99 had the best front fender. The Kawis from 94 to ‘02 looked the best overall.
 

If I had to pick one it would be the 1995 KX125.

Damn, I'd sniff that seat all day after that photo session

For me, this is the best looking factory KTM

I thought Reed always had style. I'm a big fan of the Two Two Motorsports bikes, both Honda and Kawie.

it is not beautiful what is beautiful, but it is beautiful what you like. These are some of my bikes

I always loved the look Durham’s bikes this year

To this day, whenever I hear the term “works bike,” the first image that pops into my mind is an early-mid 80’s factory Honda. 

Production Bikes

1990 KX 250

1992 CR 250

1998 KX 250

2011 KTM 450 (a particular standout)

2014 KX 450

This is and will probably always be my pick. As someone who studied graphic design it's the only bike that's really crossed into the work of art territory for me. 

I know a lot of people hate these years of Suzuki designs, but I love them. 

Those 80's Hondas are always the first bikes that come to mind for me.

Recent bikes I really liked the Motorcycle Superstore bikes.

96 mc is burned into my brain forever. 
 

I also always loved the look of this bike for some reason.