There are pros and cons to each but really the biggest factor to me is how simple the 2 stroke is. You got a crank, rod, and piston moving. That's it. IMO 4 strokes are a lot more nuanced after finally having the displeasure of working on one. Getting performance out of a 2 stroke is simple and cheap, with 4 strokes you need to buy a lot of other performance parts.
I recently purchased a Coleman ct200u-ex with a hisun 196cc honda clone, the first thing I needed to do is buy a $85+ flywheel so the stock one wouldn't fly apart and blow my leg off. Next I needed to upgrade the valve springs so it wouldn't float at higher rpms. I then needed a cam since you can only get so much out of a stock cam. There's also the rod that could fail and is another $85 but I opted not to get one. I hope the pushrods will hold up but a set of chromolys are another $35 if they bend. If I want more performance I would have to spend even more on a head with bigger valves, a bigger cam, etc. With more complexity and moving parts you need to pay more attention to part fitment as well, like coil bind and rocker angle after installing the aftermarket parts. Not to mention in my particular case it doesn't run right. It simply won't rev past about 6400 rpm and it cuts out randomly at half throttle. I fully realize that I'm inexperienced with 4 strokes but honestly I have no idea what the problem is and I can't pin down any problems.
