I don't like numbering, because I change my mind too much / see things as different but equal. So I'll list them in the order I played them.
Assuming we're talking 3d melee action:
DMC1 Shinobi (ps2) NGB NG2 Bayonetta
Vanquish really wants a spot but it it's kind of a shooter. DMC3 I've always been rather torn about, since I love most of the boss fights and hate basically everything else. Hurricane Pack NG might well replace NGB on that list if I ever decide to actually get off my ass and play it. God Hand probably belongs but I haven't played it very much, don't really know anything about the mechanics. And I really love God of War 2 but it's just not quite slick enough to make it in there.
Oh, yeah, and then there's Rising. I love Rising, but it's not top 5 for me. A Special Edition of Rising with all DLC included, some tweaked mechanics and a couple extra levels in the campaign with new bosses might make it, though.
"The act of treachery is an art, but the traitor himself is a piece of ****." - Mike Tyson
I know what you're thinking with that last one. How the **** is that piece of trash on there? Well, it probably would suck if I played it again today. But when I first played it, despite it's flaws, I loved it. The music sealed the fate for me and I had a very good time with that game. So that's why I put that on there based on my experience rather than how the game is. The others I put there based on how the game actually is.
As for a 5th one, I can't pick. It's not DMC1, not any of the God of Wars, not Bayonetta, (nope). I'd probably have to say it would be another experience one like Castlevania would would then be either Legacy of Kain Defiance, Shinobi...I dunno.
Btw, anyone know the name of this game? I think they used a real life Japanese pop star to be the hero and it started with a "B." The only thing I can tell you is the beginning of the game would start and you would have a certain time limit to fight the enemies. Once it's over the game would replay the entire battle you just did using different camera angles, then the real game would start.
I never made it past that because a friend and I literally timed how much time there was and we took turns trying to make it look cool, one person playing while the other didn't look until the replay. Then we'd reset the console to switch turns lol.