OK,
there is a lot of good and bad advice here, let's weed some out, shall we?
2 strokes are inherently STRONGER than 4 strokes, with a more narrow power band, so the weaker comment eliminates that answer.
Rebuild every 2 years? How many miles? Ignore that one!
Do you know what is involved in rebuilding the top end of a 2 stroke? You should! It is not much harder than a tune up on most cars! No legitimate shop will get their boat payments from you! If you just need rings (this is very often the case) you might be into $20.00 in parts. You need the gasket for the cylinder to the crankcase, because it will tear removing it, but the head gasket is most often reused.
My yamaha Zuma had 15,000 miles on it when I sold it, and it was never rebuilt (only 50cc), and I ran it like I stole it, so that statement is also not valid. Synthetic oil is the key to longevity on these engines (not to mention cleaner).
If you are going for a road bike, I would recommend 4 stroke, they are cleaner for the environment, and the wider power band is an advantage.