I use the regular toilet and bought a Cushie Tushie (spelling?) from Wal Mart. We liked that because it was soft, white, and (for boys, not a problem for you) there was no "splash guard" that just got in the way, just a slight raise in the front. My son is 3 1/2 and hasn't used it in months as he prefers to sit on the regular seat.
I was given a frog potty, though, which is nice because the seat and bowl are one piece (easier to dump and clean) and the frog's eyes are raised in the front, again making it a block for spray but not something that is in the child's way. I will probably use that for my younger child because he likes to sit on something when his big brother is in the bathroom.