All fantastic games.....though I can't speak for the homebrew.
Some I'd recommend are:
Castle of illusion, world of illusion, comic zone, ghouls and ghosts, dynamite headdy, e-swat, both Ecco the dolphins, and any sonic of the three (my fave is two, it's the one I played when I was a kid before my brother sold the Genny and we remained a Nintendo family until my collector years)
Splatter house games are fun too if you want to pay a premium.
I admit that I am still learning the library. Im sitting at just under 50 myself, but if you ever want to talk Dreamcast, I can have a deeper conversation there.