for fighting, online is the worse way to do. i stop playing soul calibur and tekken online, because online lag generate the worse experience on fighting games i ever experience, and for this reason, i disconnected my consoles from online. in fact, i don?t have any interest on any online game, starting with fighting games, where lag don?t let me to do most of the fake/cancel moves to trick to my opponent.
for serious fighting gaming, i prefer to play directly on arcade machine (i love Soul Calibur 2, as my favorite fighting game, with TTT and Marvel vs Capcom series), or as alternative, playing in my home with my X-Arcade Tank Stick (dual player). this is the way i enjoy playing "seriously" these games. (or, of course, in any tournament event in my city, where i can use any of my arcade sticks)
For normal play (on train, bus, etc), i use any portable device (i prefer PSP for playing Tekken 6, or S5110B for Marvel vs Capcom).
but, thanks for your invitation.