2003 Shredder, hands down, no question!

1987 Shredder: What a goofball. In the first season he was slightly threatning, but after that, it all went down hill. Turtles Forever made him go from slightly ignorant to slightly retarded, so that made things worse!

2003: This is the series I grew up with, I found him to be threatning... well at first. When he was revealed to be an Utrom, it felt like a stupid decision, even when I was a kid I thought it was stupid and tried my best to pretend it never EVER happened.

2012: Overall, this guy's the best. He's behind the scenes, and it works. When he does fight the Turtles, things get ugly, and it's just cool. It seems he's unstoppable and he reminds me of movie Shredder (my personal favorite out of all the TMNT adaptions). So he's my pick for best cartoon Shredder.

2003 Shredder actually killed people, and tried to wipe out all existence. I love KMR and 2012 is decent, but not nearly as intimidating or scary. Just because Ch'rell was an utrom doesn't mean he wasn't frighteningly dangerous.

Okay, guess I feel like it's my turn to talk about my 10th favorite fictional villain of all-time, The Shredder on each of the incarnations:

1987 ver. - Well, where do I start with this interpretation? I kinda feel very sorry for '87 Shredder that he intimidation factor isn't on par with his other incarnations. I know in that show, he's targeted as a butt of a villainous joke. Shredder has to put up a lot of shit to go through, such as mutually working together with Krang, dealing with two bumbling henchmen, and whines every time when the Turtles succeeded to foil his plans. But, that's not saying that I don't like this Shredder. I find him very hilarious, and I always love James Avery (a.k.a. Uncle Phil)'s voicework. Even there are times that he has his own sense of humor such as "Roll the camera and out! I've always wanted to say that!" and "Sorry to wake you up OIL-y out of bed! Why should they have all the bad puns?" Oh, and dare I say, I like his purple cape? Yeah.

2003 ver. - I don't really have much comment on this version, but I gotta say that the design and his voicework from Scottie Ray are badass. Though, as I agree to most of the TMNT community, I don't really like the direction that Saki was an alien at the whole time. Then again, in a very little bit of respect of this direction, I feel it's more of a nod to 1987 villainy with Krang, so.... And to give credit with this Shredder, in "Turtles Forever" he knows how to amp up the difficulty for the Turtles, by upgrading the robotic Foot army, creating monstrous mutants, combining the Technodrome with Utrom technology to make it an incredible weapon of destruction, and pushes "evilness" to highest level by trying to erase all existence by destroying the original universe of the TMNT.

2012 ver. - I have yet to see more of this Shredder in action..but right off the bat, he's badass! Even his voice acting from Kevin Michael Richardson is excellent, gives me the chills. Of course, I like the idea that he's after Splinter for a payback on whatever, that bring a lot of suspense, leaving me to keep wondering what's his beef to him (although his scarred eye may give me a clue).

So...as far as I can see, this is a tough decision for me which one I like the most, because I like all of them. However, as of now, I feel the 2012 version would win at my vote for two reason: He's not a loser like "Tin Grin" and not an alien like "Chr'ell."

2012 and 2003 are Scary and awesome

80's shredder is Funny XD

2012, faster, stronger, taller and more sharper than ever. hehe pun in tended

I can't choose!! I like them all! I grew up with 2k3 and found 1987 at the library and fell in love instantlly. I haven't seen much of 2012 TMNT because we don't have Nick.
@TheSarcasticDragon: I like capes also it makes him look cool.

I think the reason the 2003 Shredder seems creepy, is because the 2003 series is more (um...) 'serious'. Where as, the new series and the 1987 series seem to be directed towards a younger audience.