The Chameleon64 also runs D64 and T64 images, plus certain CRT images... and a lot more too.
However, like you said, it is a pure C64 cartridge and won't work with a C128.
I can't comment on the 1541 Ultimate as I've never owned one, but I did have a MMC Replay. Once I got the Chameleon64 I put my C128/MMC aside and now I just use a C64C/Chameleon combo.
Don't forget the Spectrum core. I have it loaded on my Chameleon along with the Minimig core, but I've never used a Spectrum and so I don't know what to do with it.