1. Senpai ga Uzai Kōhai no Hanashi by Shiro Manta
2. Oji-sama to Neko by Umi Sakurai
Okay, I can respect #2. In a fair fight, this and that are pretty much tied—by which I mean, both complete and utter masterpieces that I never expect to see the likes of again.
I haven't read #1 but I'm automatically dubious as to whether it could possibly be better than either of these, simply because I can't believe that one publication has that many masterpieces running at once.