There are many options out there! First off figure out what it is exactly that you want.... quality, dependability, start looking into a 4 stroke set up. It will cost more money to begin with but will save in the long run
If you want to simply just have fun and cruise around town, a 2 stroke works just fine. With a 2 stroke you will of course have to mix the oil / gas and you will most likely be tinkering with it often. I have only had 2 stroke kits and have enjoyed them very much.
Not sure if that helps at all, just my opinion. I would strongly suggest doing some research on this sight regarding safety. Be sure that when you get your bike cruising strong, you can also stop strong. again just my 2 cents