Krashkart,
Hi. I do a fair bit of instructing and the AIRtronics looks good to me as well. If you are going to be on a buddy box, as student or as instructor, take that into consideration.
As far as planes go though, Sig's LT 40 is hard to beat. I learned on the Goldberg planes and they are a VERY close second IMHO. Goldberg Eagle (II) on floats is a blast as well.
Pm me if you would like info on making a trainer into a water ready convertable.