Haha thanks for asking. It was pretty random. I have accidentally turned on SB XLIX without watching single minute of NFL before and I got hooked up. It is really funny that I had no idea about any rules that time and had no idea who Brady or Patriots were But the game was great so I decided to check it next season. Then early in the season I saw Bills game (looking back I am pretty sure it was Bills/Pats W2 loss, since otherwise Bills wouldn't be televised in Europe), and I really liked Tyrod's play style - it was different from what I saw from other QBs. So I started to watch him more, started to watch NFL regularly, found BBMB and became Bills fan
But you are correct assuming that Bills don't have many fans here (and in Europe in general). Pats, Cowboys, Seahawks, Steelers, Packers, Eagles, Giants, Saints, 49ers and Raiders are fan favorites here.
Oh and I have great relationship towards USA in general, was there couple times as a college student for summer work and travelling (was twice in Bufallo/Niagara Falls years ago), so it wasn't hard for me to fall in love with NFL. Funny thing that I spent whole summer 2002 working in Scomas restaurant in SF which was full of pictures of NFL (and probably also MLB) players, but at that time I had no idea who Montana or Young were...