get a yamaha can't beat them! we have a 2005 3 seater with over 300hours still runs like a champ, and 2 gp1300rs 2stroke that are amazing, for reliability get yamaha. seadoo puts a bunch of other crap thats unneeded and can't stand up to abuse or salt water. also maintaining them is super easy do ll the work yourself and you can learn a lot about them on forums like greekhulk.net
also i just bought a 650 superjet standup, now that is true fun!
when buying used do a compression test on it, and look for signs of salt water use. salt water can really make these wear out faster but if you do the proper maintenance that wouldn't be a problem. id look into a yamaha 4 stroke that way you don't have the added expense of the two stroke oil all the time like i do with my gp1330rs