Let's see... US/UK (just classic but idc they're so cute and ugh I'm never going to get bored of them ok), Prussia/Austria (OTP OTP OTP /CRIES), Spain/Romano, Denmark/Norway, Sweden/Finland, Germany/North Italy (classic²), and Russia/Everyone although I actually ship everyone with everyone in this series since it's so goddamn slashable, I don't even. e///e
mmm germany x italy spain x romano france x austria (OTP) USUK england x japan denmark x norway sweden x finland russia x china :3
Definitely Germany and Italy! "Doitsu, ohayou! Hagu shite, hagu shite!"
Well, I have a lot of favorite pairings in this series but I will list them down nonetheless USUK DenNor SpaMano PRance (PrussiaxFrance) HongIce RomaBul (RomaniaxBulgaria) PruHun LietPol RusLiet IceLiech and some more but I can't remember all of them so I might edit this later.