I haven't flown much longhaul, but I can comment on hubs. I find the AZ hubs (particularly FCO) far nicer places to transit than CDG. For a start, they're not as big/crowded as CDG so there's fewer people moving about creating noise. The AZ extra-Schengen lounge in Rome is quite nice, too.
And most airport workers (not just airline employees) seem to speak English which is a big plus when you 've got to be at gate Z998 in 3 minutes and for some reason can't find/understand the signs.
So IMHO Alitalia wins hands down in the ground/transfer department. Another positive for AZ is that it offers (nonconvertible) F class seating in shorthaul- it is AFAIK the only European airline to do so.
But you'll have to rely on others for opinions on the longhaul part!