Marvel Vs. Capcom Ex Edition aka the PS1 version is very fun, yeah it's not arcade accurate at all and most wouldn't like the 1v1 system, the infinite assists or cross over mode being a diet version of the tag game, but I like what it brings like being able to combo specials into supers (later implemented in Marvel 2), comboing supers into another super, choosing any assist without using the button combinations and other neat things like Mega Man being able to use Magnetic Shockwave.Not sure how it fares balance/competitive wise but the arcade game is already very busted ha.
MvC1 on the PSX was soul, especially if you were also playing other Capcom games on the console at the time. Seeing Rock have some of the same weapons like the Mega Ball from MM8 was mindblowing to me. Felt like the games were all connected.
I think about the ps1 ports from time to time and think "why not have 1 on 1 matches?"
I have a Metal Slug 3 MVS cart, and I still prefer playing the X-Box port of it.