I upgraded my handheld emulation setup and can now do up to Dreamcast (N64 and PSP too) on the go but I don't really know what to try out. There are a couple of DC games I've played the PS2 versions of like Resident Evil: Code Veronica and Dead Or Alive 2, which I used to test out how well Redream and Flycast worked but beyond that I'm not sure what to grab 
It would be fun to give Saturn emulation a shot as well but I'm not sure if it'll even be playable. From what I've read, in terms of emulation on Android devices, Saturn sits somewhere between the DC/N64/PSP tier and the Gamecube/PS2/3DS tier in hardware requirements. I figured I might as well ask for MD/Genesis recommendations to round out the Sega systems.
These three Sega consoles are my childhood, Saturn is one of my favourite consoles despite it being generally seen in a negative light.
Mega Drive:
Story of Thor
Chaos Engine
Micro Machines games (2 turbo tournament was my fav)
Sonic games but specifically I really loved Sonic Spinball as an outlier.
Mega Bomberman
Bonanza Brothers
I could go on but I don't know what you have played before without just listing the greatest hits like Streets of Rage and the like.
Saturn:
Nights Into Dreams
Panzer Dragoon Saga
Guardian Heroes
Darkstalkers Revenge
Burning Rangers
Fighting Vipers or Fighters Megamix
Die Hard Arcade
Sega Rally
Sonic R
Saturn Bomberman (the greatest bomberman version that exists IMO)
I strongly recommend just exploring the Saturn in general as there is some great stuff out there, some of it janky as fuck but it is of its time.
Dreamcast
Space Channel 5
Power Stone 1 and 2
Crazy Taxi
Jet Set Radio
Chu Chu Rocket
Rival Schools (some amazing special moves in the best em up, I always remember the synchronised swimming guy)
Shenmue
All of these consoles are worth exploring though and these are just a few that come to mind straight away for me.
I started with the PlayStation so both the SNES and MD are a bit before my time. I have delved into the SNES catalogue since there's lots of well-known and still talked about games and series for an easy jumping-off point. Streets of Rage isn't actually a bad recommendation at all, it'd probably fit my handheld use case very well. Do you have any favored Mega Drive/Genesis emulator on Android? I assume there's a RetroArch core (or three) for that
I have no idea I'm afraid. Never emulated on android, I used to use I think it was called K Fusion on PC for a bit but tbh I've mostly played on original hardware :)
Bonanza Bros is a classic for me. I had it on the Master System but it ran better on the Mega Drive. Funny, full of character, stealth platformer where you get to shoot cops / security / agents / soldiers while doing crimes and using Laurel & Hardy style disguises. Basically proto-Hitman.
Ah, didn't know it was on the master system as well. I started my video game journey when I was 5 with a Mega Drive and never really played much master system beyond one Alex the Kidd game!
I don't see bonanza bros mentioned very often though, glad someone else appreciates it :D
Yeah, it definitely feels underappriciated and I haven't known many people who played it. I'm old so I started with a ZX Spectrum, had it for years, then later won a Master System in a magazine competition and played the hell out of it for years as we were too broke for a Mega Drive until quite a few years after it was out and a family friend sold us his old one on the cheap with a bunch of games.