Openings:
Overman King Gainer OP vs. Slayers Try OP - As much as I went into this expecting to vote for the Slayers OP, and as much as I hate the design of the mech in Gainer... holy crap that was a fun opening.
FMP Fumoffu OP vs. Bleach OP1 - On the other hand, Fumoffu's OP put me to sleep.
Ghost Hound vs. Durarara!! OP1 - I like the jazzy Ghost Hound song, but the visuals are even more boring than Fumoffu's.
Code Geass OP 1 vs. Sailor Moon OP1 - Code Geass, somehow, has the worse song.
08th MS Team OP vs. Tenjou Tenge OP - MS Team is 'Yay, 90s!', but... it's not even very good 90s. Really generic. Tenjou Tenge OP is far more memorable and creative, whether you like the rap or not, it's certainly got a clear style and unique energy.
Lodoss OP vs. Area 88 OP - When your featured action is poorly-CGed planes, well... Lodoss War can beat much better than this.
Lain OP vs. Read or Die OP - Despite Lain being my nom, this is a REALLY close match. Both OPs do a great job setting up their respective show's tones, and they both have really unique visuals styles. In the end, it turns out that I actually like the high-energy character-centric OP better.
Gankutsuou OP vs. Clannad After Story OP - I actually don't really care for the Gankutsuou OP much... but the Clannad OP is terribly boring and generic.
Endings:
Magic Knight Rayearth ED1 vs. Noir ED - Wow, you know, Rayearth has some decent OP/ED stuff, but not this one...
Soul Eater ED4 vs. Deltora Quest ED1 - Not close, despite Deltora being pretty decent.
Vandread ED vs. Kimi ga Nozumu Eien ED - KgNE needs to die in a fire.
Digimon ED1 vs. Kimagure Orange Road ED2 - While I actually kinda like the Digimon ED there at the end, this particular KOR ED is pretty awesome for 80s stuff, and I really dislike KOR's style of just about everything.