I have the Baby Bjorn seat for DS, but it's really not comfortable for him. He's constantly repositioning trying to get comfortable on it. I think I would rather have a seat for the regular toilets than a stand-alone potty. TIA!
We have a Mickey one that sits on top and an elmo one that sits on top and find that they are motivating for DS because he likes the characters a lot. I can also throw it in my backpack if needed for when we are out in public somewhere.
I bought a few different seats but the only ones DS actually likes are the foamy character seats (we have spongebob and Spider-Man). Not my first choice but they're fine and seem to contain his pee with the splash guard
We have those on the 2 toilets DD mainly uses. We also have regular potty ring that we bought before switching to the integrated seat. It's the Fisher Price Perfect Fit Potty Ring and it's great. Comfortable, has a little back support, curved up on the sides so they have something to hold on to, and comes with a hanger for the side of the tank.