Red/Blue/Yellow were such a hit and Gold/Silver/Crystal were awesome
Ruby/Sapphire/Emerald kinda hit the mark but now Diamond/Pearl/Platinum and Black/White/??? have really brought it back!
 
Which version was your favorite?

I only played Yellow but I liked it a lot.

Blue, probably my most memorable game as a kid.

Gold/Silver

Red and blue all the way. Black was pretty good, I must say I really enjoyed Black's story.

Silver. Anybody who says otherwise has grossly misused their brain.

Gameplay wise? Black for sure.
 
Fuck nostalgia, that game just did so much right.

Probably Yellow or Silver...because of nostalgia. Loved playing the HeartGold/Soulsilver remakes when they were released.

Ruby/Sapphire/Emerald

I'm pretty sure the first one you play is always the best and so nothing beats Red/Blue/Yellow.

Mew is the LAST pokemon.

Gold/Silver were the last pokemon games I genuinely enjoyed.

Red and White.
 
Red was the first, White is just 2.0 of the series.

Red, but mostly for nostalgia. I think Black is overall the best game. Its the biggest step up since Gold/Silver.

Gold/Silver

Yellow or Red. As far as I'm concerned, there are only 150 pokemon and there always will be. 

One of my fondest childhood gaming memories was playing my Blue version while I was dragged to my sister's Girl Scout bullshit.  That game was sanctuary.

I've played Crystal the most.

Gold/Silver

I don't think I could name a favourite version, though Diamond was most certainly my least favourite.

red/blue..by a hair over gold/sliver

They're all the same though!

Fire Red and Leaf Green are pretty much perfect remakes of the originals. It is improved in every way. Definitely the versions to go with.

Silver. Anybody who says otherwise has grossly misused their brain.

Silver.

Yellow.

Crystal.

Blue/Red/Yellow. I don't accept any Pokemon added after those versions.

Platinum.

As nostalgic as I can be over Red/Blue and Gold/Silver, those games play like shit in comparison to games made today. Platinum had the right amount of improvements and features that it secured itself as my favourite. Heart Gold was pretty goddamn awful, and only served to make me remember how terribly designed the second generation was.

@Video_Game_King said:

Silver. Anybody who says otherwise has grossly misused their brain.

Mine is Gold, but seriously, Video Game King and I will fight anyone who says otherwise.  We will destroyyy you

Gold/Silver was the best gen. Ruby/Sapphire was the worst. Speaking strictly in terms of the actual pokemon. Black/White if talking about the actual game.

Gold. So many good memories with that game when i was a kid.

Black/White are clearly the best games. Emerald is probably my favorite, though.

I'm going to have to say Silver/Gold.

FireRed's GBA cartridge looks bitching. 
Never could get through it though.  GODDAMN IT DAYCARE-MAN, LEVEL UP MAGIKARP FASTER.

Silver/Gold, cause the final final boss was your character for the first game!

Blue.

I've also played Diamond, Gold and White but Blue is the only one I ever completed.

I sunk the most time into Gold back in the day, though Ruby and Sapphire were great too. I didn't care for Diamond & Pearl- maybe I've just done it too many times and am bored of the formula, but I just didn't like it.

My personal favorite generation was the Gold/Silver/Crystal generation, but I fully recognize that, objectively, the best is Black/White.