'03 drew more heavily from the source comics. Plus, it had Usagi, and more importantly Gen! (Sure, he was portrayed as nothing like the Han Solo type the writer claimed him to be, and more of a samurai Garfield, but still!)
2013 series is a lot more original. Personally, I like it, but it can be really hit and miss (The Napoleaon Dynamite Frog was just painful.)
As far as the fight goes, if we're using season 5, then that means powers. Which makes this a stomp in favor of '03.
I don't think they need the powers to win, though.
__________________ What CDTM believes;
Never let anyone else define you. Don't be a jerk just to be a jerk, but if you are expressing your true inner feelings and beliefs, or at least trying to express that inner child, and everyone gets pissed off about it, never NEVER apologize for it. Let them think what they want, let them define you in their narrow little minds while they suppress every last piece of them just to keep a friend that never liked them for themselves in the first place.
Nu-Turtles routinely take on more powerful enemies though and end up going from being unable to even phase them to stomping the shit out of them, especially when they go "White Eyes". I think OP meant up to Season 5, but not the ninja powers because that would just be uber stomp.
I don't know about more powerful enemies, plus sometimes turtles take on more powerful foes solo.
Like, in one of the season finales, the '03 turtles took on Baxter in a ridiculously powerful mecha (one that really blows his '13 mecha away), and then Leo-with-a-fancy-sword took down Shredder.
The '13 turtles take on some powerful stuff, to be sure, but it really requires heavy teamwork, and some like Shredder are still tough for them even as a team.
1 - '13 because it mixes a bit of everything and just makes me love it a lot more.
2 - Hmm, I kinda really like the fight scenes in '13 more.
3 - Just the turtles.. '03. The '13 turtles are kind of weak compared to their master and Shredder, but if they could rise to the level of Splinter and Shredder I would probably say '13 over '03.
__________________ If you try something stupid, and it works it ain't stupid.
Funny thing is, that fancy sword was given to him by Shredder.
For no real reason. If Splinter didn't have that sword, they never would have passed the elemental warriors.
And yes, '03 turtles faced some monsters. Utron Shredder by himself is a monster. He'd walk all over '13... heck, he'd beat every other Shredder combined.
Except maybe IDW. He's pretty overpowered.
__________________ What CDTM believes;
Never let anyone else define you. Don't be a jerk just to be a jerk, but if you are expressing your true inner feelings and beliefs, or at least trying to express that inner child, and everyone gets pissed off about it, never NEVER apologize for it. Let them think what they want, let them define you in their narrow little minds while they suppress every last piece of them just to keep a friend that never liked them for themselves in the first place.