Re: engine choices
99% of the kits are the same.
The best price is what I look for and upgrade as needed myself.
Much cheaper to do it myself than pay premium prices.
Arrow and Dax are two vendors who offer upgraded ht motors if you have the means.
If you want best reliability, I'd look into a honda four-stroke build.
If you want a racer, a Morini or KTM clone.
For cheap fun, a china 66cc two-stroke.
For Vintage, a Whizzer.
There are too many choices for us to tell you what YOU want....
If more is better, then too much is just enough.
If you can't afford it, build it yourself.