MC1 was a simple kind of fun.
MC2 had the most intense matches (CTF sudden death, Avalanche, 200+ kills with the m40 sniper).
Missed the hype with MC3 because I got it late :(
MC4 was buttery smooth, so easy to get 30-0 games, listening for enemy footsteps and using silenced weapons. Also <3 x6 with silencer.
MC5... The start of the downhill trend. Broken spawn trapping, Like BIA2 bad (Original, not that pay2play remaster), super sloooow movement and then they added a whole bunch of random pay2win garbage after it went free.
MCV... Dump a whole magazine into an enemy to tickle them