I use Grayjay, so it doesn’t tend to matter much. However, I prefer to buy songs instead, so I can listen to them far past the source platform’s end of business.

If still needed, I’d suggest sticking to 8 MB ones and dumping / restoring saves through uLaunch Elf and a a USB stick. (or similar solutions for moving to / from more standard storages)

Whatever companies publish/republish nowadays as ROMs or that include ROMs. Plenty of homebrews, specially on Itchio, and some times (albeit rarely) we get stuff from companies like Capcom, Atari and Konami. It’s always nice when that happens.

For handhelds, I have a Supaboy, a PSP, a PS Vita, a 3DS old, a New 3DS XL and a Switch.
Out of those, the Switch is the only one I can’t play emulated games or homebrews, given I haven’t modded it nor there is flashcarts for it.
And among the ones we both have, the 3DS XL models seem like the best ones. Not very heavy while still being decently sized, good resolution and color palette, buttons with good pressure, and for emulating Nintendo games, Nintendo’s own devices are usually the best for their given release period.

Mint 21.1 Xfce, and if Android counts, ArrowOS 13 (on phone) and BlissOS (on an old computer)