@ pubzombie - I'd go with a choice based on what you need. Both carts do 1541 emulaton so either would be OK for games loading.
The Chameleon goes further by implementing VGA output, higher graphics modes, MMU, CPU accelerator, blitter etc. etc. but none of that stuff is going to be any use unless you or others code things specifically to make use of those features. If you don't need or want to use those things, then probably not worth paying for them.