gonna just cover platformers, best of all timers:
Mega Man X1 - generally considered to be the best game in the series and definitely the best one to quickly make a case for megaman to any newcomer. technically got remade with Maverick Hunter X but don't do that first, please
Mega Man X4 - also a must play if you're a fan of X1. introduces zero as a playable character, proper.
Mega Man 2 - a classic that plays quite well, it's generally considered to be the peak of megaman classic and one of the best games of its era
if you enjoy these games, there's other sequels in the series that are also quite good, even if they aren't BEST GAME OF ALL TIME material like the earlier 3 are.
Mega Man X2 - a very safe, formulaic sequel to x1, that incorporates the dash from the start and begins moving toward the twitch gameplay you will later find in X4.
Mega Man 3 - a somewhat ambitious follow up to 2, it ups the challenge level a bit and has a surprising second act. it was rushed, it's not perfect, but there's quite a bit of debate between hardcore fans by which is the best between this and its prequel, and for good reason
Mega Man Zero (series) - my personal favorites. these switch to a ranking based system with generally shorter levels, encouraging you to complete a level from start to finish without dying, or using things like health upgrades. they have a notably amazing game feel with a great deal of precision and power to your tools. there's a lot of technicality to these games, but people who want to take their time might not enjoy these. smaller screen real estate due to the GBA can also be an issue at times, most notably in the first two games, but it's nothing that can't be worked with.
Mega Man ZX - a follow-up to the zero series, removing the ranking system and adding a form system that lets you essentially swap between 5 armors with different playstyles on the go. it's technically a metroidvania, but just technically... the map is kinda rough and abilities from these new forms aren't used too much in unlocking new areas. as with the zero series, there's also a lot of depth should you choose to seek it out
then there's some more... troubled, flawed games that are still good but maybe lower priority, absolutely worth playing if you are loving the series.
Mega Man - the very first. it's actually surprisingly competent, but it's got some rough spots here and there and isn't quite as compelling as the two follow-ups. yellow devil makes people upset until they learn what the select button does. has a FANTASTIC remake in the form of Mega Man: Powered Up, adding a level editor, playable bosses, unlockable slide and charge shots for megaman, and all sorts of other goodies. underappreciated gem.
Mega Man 4-6 - the NES sequels. a lot of people reactively hate these, but they aren't bad at all. they're actually quite good. the problem is that there's THIS MANY OF THESE within the span of just a few years. 4 is a very well polished entry, 5 is a great beginner friendly title with a great jazz inspired soundtrack, and 6 is a surprisingly impressive little beast that adds two armors for megaman on top of an impressive presentation.
Mega Man IV-V (GameBoy) - surprisingly good entries with really fun levels, megaman IV in particular is hugely overlooked when it takes elements from 4-5 on NES and does them far better than the originals. V is an entirely new game with original bosses, and it just got a color patch recently!
Mega Man 7 - made in 6 months by a lot of the staff from classic's best, it's quite the decent game. introduces a new fan favorite character, and plays a LOT like the gameboy games. it feels like it's a successor to those, in a way.
Mega Man & Bass - a very strange bonus game, it's another game in the style of 7 and the gameboy games, but graphics from 8! it introduces Bass as a playable character, who has the ability to dash and dash jump like X, double jump, and fire shots rapidly in all 8 directions. the game is very difficult, especially if playing as megaman, but i still enjoy it a lot. avoid the GBA port at all costs.
Mega Man 8 - fans are REALLY divided over this entry and a lot of classic fans jump off here, it goes hard on a new presentation and changes the perspective to be more like x4-6. very detailed animation and art, complete with animated cutscenes. i actually like this game a lot!
Mega Man X5 - this game feels like it's rushed, but it seemingly wasn't...? has some strange pacing issues and mechanical oddities, many of which are ironed out thanks to fan patches, but people are a bit divided over this one. it's my favorite X game for how much slower paced it is, with a lot of screens asking you to stop for a second and think about how to clear the way.
Mega Man ZXA - a perfectly fine and serviceable sequel to ZX, but it removes a lot of the mechanical depth from that game, and introduces playable forms for all of the non-humanoid bosses... which would be right up my alley, except they all suck and are basically unplayable outside of puzzle rooms. biometals not being unlockable immediately puts a huge damper on this game.
Mega Man 9 - this game had quite a bit of novelty at the time due to being a revival of the classic, NES styled megaman. a new NES game made in the late 2000s is CRAZY. the level design is way cheaper than the original games with a lot of "gotcha" moments. the most notable example being, with many of the pits in the game, when you jump over them, enemies can jump out from the pits out of nowhere and instantly drag you to your death
Mega Man 10 - it has less obnoxious level design but also wasn't really what anyone wanted from the series at the time, it's the definition of "okay." can play as bass through the collections or DLC and he can still dash jump, though it's awkward to use.
