I'll put in a vote for a SIG LT-40. I converted mine to floats after moving from basic trainer flying and it is a ton of fun. If you want e-power just set it up that way. I built my floats from scratch but you can put RTF floats on it if you want. I'd recommend putting "60-size" floats on because the LT-40 is really a 60-size airframe with a 40-size motor. The typical "40-size" floats you buy are just a bit too small and will sit too deep in the water, IMHO.

Small float planes are ok if you have really calm water but where we fly you'd have trouble with the waves if your plane was much less than about 48 inch span.