Mega Man 1 is a fine first entry. Rockman Complete Works is a really nice overhaul of the game that adds in quick weapon switching similar to Mega Man 7 and 8. There's also new music ripped directly from Mega Man 2 The Power Fighters which is available in the game's "navi mode" along with many other quality of life features such as saving. Quick weapon switching helps to make the game feel more fun and takes a game I already think is enjoyable and makes it a little better. If you want a new and fresh way to play the game, definite give this one a try.