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.

There are also games sold/distributed only as ROMs you can run on emulators, if you'd be interested too.

I'm seldom picky about what I play. So, by extension, expect to see little to no consistency in what I'd recommend:

#hasicontent
8Doors: Arum's Afterlife Adventure
A Vampyre Story
ABZÛ
Atari Vault
Batman: Arkham Asylum Game of the Year Edition
Batman: Arkham City - Game of the Year Edition
Battle Chef Brigade Deluxe
BlazBlue: Continuum Shift Extended
Bloodstained: Curse of the Moon
Bunny Swordmaster Story
Catherine Classic
Celeste
Celeste Classic
Celeste Classic 2
Child of Light
Dandara: Trials of Fear Edition
Devil May Cry 4
Devil May Cry HD Collection
Downwell
Dreaming Sarah
Dusk Child
Dust: An Elysian Tail
Etherborn
Final Fantasy VI
Final Fantasy VII
FINAL FANTASY X/X-2 HD Remaster
Final Fantasy XII The Zodiac Age
Grey-Box Testing
GundeadliGne
Gundemonium Recollection
Hitogata Happa
Injustice: Gods Among Us Ultimate Edition
Ittle Dew
Kimmy
Kitsune Zero
Knight Club
LiEat
Mary Skelter 2 & Mary Skelter: Nightmares (revamped & retconed version; included as an unlockable in Mary Skelter 2)
Mary Skelter: Nightmares (OG version; still being sold)
Metal Slug
Metal Slug 3
Micro Mages
Minecraft
Minoria
Mobile Light Force (aka Gunbird)
Moero Chronicle
Momodora
Momodora II
Momodora III
Momodora: Reverie Under The Moonlight
Ni no Kuni: Wrath of the White Witch
No More Heroes
No More Heroes 2: Desperate Struggle
Okami
One Strike
Phoenotopia (Adobe Flash version; didn't play the remake yet)
Portal
Rabi-Ribi
Remember Me
Riddled Corpses
Saints Row: The Third
Senran Kagura Bon Appétit
Shantae and the Pirate's Curse
Shantae: Half-Genie Hero
Slay the Spire
Slipways Classic
Songs for a Hero: Definitive Edition ("A Lenda do Herói - Edição Definitiva" in its Portuguese name)
Starbound
Super Dungeon Boy
Tanglewood
The Corruption Within
The Deed
Unparallel
Va-11 Hall-A: Cyberpunk Bartender Action
Wake Up
Wishing Sarah
Wonder Boy in Monster World | Wonder Boy V: Monster World III
World of Final Fantasy
コテ・DE・メクール
真・魔王ゴルベリアス　先取り横スクロール面

Some years back, this might've been an alluring thought. But now, I think in the lines of "there isn't a cure when there's no disease". If anything, more and more, I see new strengths to be explored in this "issue" that is autism (as well as it "sibling condition", ADHD).

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