It depends if it's in an actual arcade or just arcade games as a whole.
I've been using MAME since its initial release in the late 90s.
I also love numerous music games, but I'll talk about them more properly in a different question.

My most commonly played games in real arcade settings were DDR 3rd Mix Korean V2 (at a skating rink I frequented), DDRMAX2 (at a proper arcade many years later), DDREXTREME (they upgraded it), Soulcalibur II (at that same arcade), Raiden II (I got really good at it, now I can't play it worth squat though), Mocap Boxing (although I wore out my arms every time!). I also, as a little girl, took trips to a science museum where they had a Virtuality 2000SU machine with games like Zone Hunter and I enjoyed that greatly at the time. Can't even emulate that stuff today, what a world...

Through emulation, the one I fell most in love with is Salamander 2. I was following blog posts about MAME work to get games working, break their decryption, dump them, etc. And when Konami GX emulation finally came into being, I tried every dumped Konami GX game. I loved the Tokimeki Memorial puzzle game, stuff like Parodius was great... but I really, really clicked with Salamander 2 and it remains my favorite horizontal shmup to this very day.

I've talked in a previous answer about my love for Numan Athletics, and I do absolutely adore that game. It's so funny, so challenging, and makes a great game to just sit down with a friend or two and play any time. The sequel Mach Breakers is... all right, but it's missing a certain I-don't-know-what.

Broadly, through MAME I was willing to try just about anything. I found many fighting games I enjoyed, and got into King of Fighters despite only being exposed to Street Fighter for much of my life. My favorites are 98 and 2000.

I also very much love Twinkle Star Sprites and Magical Drop III.

My favorite Metal Slug game is Metal Slug 3, but in actual arcade settings I mastered Metal Slug 2 for a time. The sheer amount of lag made it an exceedingly easy game to 1CC, probably more than any other in the series. Can't blame them for making Metal Slug X, the game really deserved a better re-release and it's good that it got one... even if it's a shame you can't play it in any sort of "original mode" without the other changes X made.

My favorite vertical shmup is ESPRa.De. I've never had the pleasure of playing on a real cabinet, but I've been emulating it on MAME for ages and I own the console port ESPRa.De. Psi which is very good.

I've played Rampage World Tour on a real cabinet with other people numerous times when I was younger, though I now consider it to not be that fun of a game past the first 10 minutes or so, unless you've got a group that's really funny and talkative. But then, what game isn't great with a group like that?

My favorite Capcom fighting games are Capcom vs SNK 2 and Street Fighter Alpha 3. My favorite outside of Capcom and SNK proper is Rage of the Dragons. I've never played any of these on real cabinets, but I invested a lot of time in Marvel vs Capcom 2 at an arcade when it was new. It was really something being there at the time, having absolutely no idea what new characters would appear after enough play. It wasn't something everyone knew in advance, so you found out in a similar time frame to when anyone else did, and it was a surprise every time.

I was the local ace at Initial D Arcade Stage ver.2. I regularly stacked many wins in a row, which would give your car an "aura" that got bigger and more intimidating the more wins you would get. I had a rainbow aura on my car a few times. I unfortunately would get very upset if I lost however precisely due to the fact it meant I'd lose my aura...

In Soulcalibur 2, I was never all that great, but Conquest Mode was a big thing at the arcade I was a regular to. The most outstanding player was a guy called "DanTheMan". It seemed like no one knew exactly who he was, but he was a really powerful Nightmare player. I eventually entered a tournament at the arcade with one of my friends, and DanTheMan was also an entrant. He, of course, wiped the floor with all of us, but we were just happy to get even a single win before facing him. Mythological tier stuff.

The arcade had a Cyber Sled machine for a few weeks and I became briefly very enamored with that game due to the general presentation of the game and its cabinet.

I finished Gauntlet Legends on a real cabinet once. Not a lot to say about it but clearly I enjoyed it if I kept going at it until I got through it like that. It was the original release, not Dark Legacy.

There was also a period where I had a lot of hours on Mortal Kombat 3 at an arcade, and was considered one of the better Sub Zero players. I don't really like Mortal Kombat that much anymore. Well, I like the lore and characters, but the gameplay, I really dunno...

This is starting to come off as just a huge list of various games I ever played, so I think I'll draw my response to a close. But I was a huge mall rat and arcades were one of my favorite things ever. I really miss that experience a lot.

I don't even think the games themselves are as important as the overall vibe and experience, and we as a culture have lost the narrative on that one, replacing arcades with Dave & Busters type experiences designed to only keep your attention for a few moments, which I'm sure is more profitable, but an entire kind of community is basically gone unless you live directly around one of the remaining real arcades out there.

I like beat em ups and shmups mostly.

When I was little I started with Konami licensed games like TMNT, The Simpsons and X-Men. But my favorite out of that genre has to be the two Capcom beat em ups they released based on Dungeons & Dragons, Tower of Doom and Shadow over Mystara.

I have played a lot of shmup games over the years. Standouts to me were games like Strikers 1945 and Raiden II. But my favorite by far has to be Jikkyou Oshaberi Parodius ~ Forever with Me ~ due to how silly it is and trying to point out all the Konami game references in it.

And then there's fighting games. I used to love playing Tekken, Street Fighter and Marvel Vs games at the arcade. I thought UMK3 was awesome but I'm not all that great at Mortal Kombat 😅