The more rare, obscure, or just a guilty pleasure, the better. Maybe you grew up with it, maybe it’s just the nostalgia talking, any reason is fine.
I’m looking for a new game to play, but I’m running out of games to collect!
My favorite is games for original DMG, but you’re welcome to include Color it’ll advance games too!
There are colorized versions available, made by community, but really well done.
HIGHLY HIGHLY recommend the DX romhacks you're referencing, IMO they enhance SML/SML2 to the point where it's just better to play the hacks instead unless you're stuck on a monochrome GB.
Super Mario Land DX - https://www.romhacking.net/hacks/4477/
Super Mario Land 2 DX - https://www.romhacking.net/hacks/3784/
(Original ROMs to patch required, not at same site.)