Mine is Sly Cooper, I used to just explor the worlds in those games for hours when I was a little kid, and I still love the series, it's got great gameplay, Chracters, story, humor, and dialogue. So excited for the new one.

"Series"? Ratchet & Clank, the most consistantly great platforming games around. Sly Cooper is a close second, though. That said, I love tons of one-off games and series that mostly sucked outside of one or two games. Super Meat Boy had a prequel that was pretty bad. Super Mario Bros. and Super Mario Sunshine are the only great Mario games as far as I'm concerned. Cave Story was never a series. Sonic is the most uneven series ever created - so many fantastic games, yet so much crap as well. I could go on, but I think you get my point. There are very few great platforming series in my opinion.

3D Mario titles for me. Mega Man as a whole is something really great, too. Ratchet and Clank is a series I've found to be pretty consistent in its quality as well, although I wouldn't say any of the games are really as great as Galaxy or 64. As for other series out there, it's tough, mainly because there really aren't a ton of series that have been great across the board, @CanisWolfred said. Sonic is all over the place, tons of platformers only have a single entry, etc.

My favorite Platforming series belongs to New Super Mario Bros. but my favorite platformer is Donkey Kong Country Returns.

Super Mario World 2: Yoshi's Island is the best platformer ever.

I know, it's not a series, but it's so d*** good.

Mario... nuff said!

Yeah, series would go to Mario along with my favorite platformer (first Galaxy) but loads of other great platformers exist that aren't in series which I prefer over several Mario titles (Braid, Super Meat Boy, Bionic Commando Rearmed)

Pretty much this.

Most of my favorite platformers come from the Mario series, so I guess that would be my favorite platformer series. Honestly, you're on a Nintendo site. What kind of answers are you going to expect?

I'd say the Super Mario series is my favorite, with Super Mario World (on SNES) being my favorite.

Quoted again to prove its worth.

Anyway as far as Platforming series go, I'd choose the Mega man Classic series. All of the eleven main games, which includes Megaman and Bass, are all solid Platformers in their own right, even MM8 with all the backlash it gets still has its own merits of being a good platformer. I also think the Mega man Zero games has been consistently great.

Metroid if that counts, with Castlevania being a close second.

My favorite overall is Donkey Kong, but my favorite 3D platformer is the Sly series.

Agreed, 2nded, whatever. Of course it wouldn't count because the Yoshi series dropped in quality almost immediately afterwards.

I'd say Mario, no matter how cliched it is. Yeah I complain about the NSMB games but they haven't necessarily brought the series down too much, assuming this is really the end of that series for a while. But even lesser games in the series like say, the Land games or whatever I still think are really fun and really get a lot of enjoyment out of.

I'm seriously trying to think of a platformer series I've played most of other than that and spinoffs with different characters. I mean Sonic would be up there if it wasn't for 2006. Castlevania too, though I wouldn't count SotN or beyond. Also, Kirby. Genuinely wish I had less cliched answers but sometimes popularity makes complete sense in terms of consistent quality.

I mean, the only Playstation platformer series I'm familiar enough with the good games are the old Crash trilogy.

Jet Set Radio

Stylistically yes, it's awesome, but the camera bugs me a little. I wonder if it got fixed in Future, because playing through some levels in the original was a chore, even with a camera fix option in the HD port

If it wasn't about a series, it would be a lot easier to answer. I guess I'd have to say Mario and Kirby, and does Metal Slug count?

Metal Slug definitely doesn't count. :/ It's a side-scrolling shoot 'em up.

I guess metroid.

I feel unoriginal here, but like everybody else said, yoshi's island is the best platformer ever, no contest.

1) Super Mario
2) Donkey Kong
3) Banjo-Kazooie
4) Ice Climber
5) Billy Hatcher and the Giant Egg

Would Castlevania count? All the 2D games from 3 onwards were fantastic. All the handheld games were top-notch, too.