We have a safety 1st potty that we probably bought at target. Very basic, not the most compact, but very durable and can be used as a step stool. We also have the elmo padded seat that fits onto a regular toilet. My daughter started out on the training potty at a year, and moved to preferring the elmo potty seat because she wanted to be a big girl and use the big potty like mommy. So I turned the potty over and she was using it as a stool to get on the big potty(I have always had a separate stool for the sink). She was potty-trained before she was two, but she was very protective of her bathroom, she didn't want anyone to use her potty, and since her bathroom is also the guest bathroom that posed a problem when we would have company. She regressed for about a month when my newest baby was born 8 months ago, but we didn't make a big deal about it and she went back to panties of her own accord. Her friend across the street began potty training and got a Dora training potty(maybe smaller than the safety 1st, but I don't think it has the stool capability) which they kept in the play room and not the bathroom(another option) and my daughter fell in love with it and told me she wanted a little potty too. I flipped that stool over immediately and presented her with her very own little potty and so now she prefers the training potty. Ownership means alot to them at this age. If you get a plain potty you can help her decorate it with stickers.
Good luck and don't forget to get some "potty" books not just the ones about going to the potty, but ones about everything else that you can read together while she is sitting on the potty.