For me, the choices are pretty easy. In order:
1. AKB48 - UZA - Easily AKB48's most solid single, in my opinion. An amazing A-side song and PV, terrific B-sides, all around a great release. Probably my favorite AKB48 single yet.
2. NMB48 - Virginity - Catchy, fun, scandalous... I really love this song. It's so different and... odd.
Only NMB48 could make this work so well.
3. NMB48 - Nagiichi - I love the summer releases, but Manatsu no Sounds Good left something to be desired. Luckily, NMB48 delivered. One of the best summer bikini-ridden releases ever. Great song, great visuals... nothing was wrong with this release(for a summer song).
4. SKE48 - Aishite raburu - Fun summer release, pretty well done, energetic as all hell as we've come to expect from SKE48. Not quite as awesome as Paleo wa Emerald, but still really good.
Looking at this list, there's only one release I have a problem with: SDN's graduation single. What a waste of great girls letting them go, and what a shame they left on such a 'meh' song.
Still, all thing's considered, we had another really great year in the 48 empire.