Well, is it? It's something I often wonder about myself. Growing up I'd have always said football, but these days I find I don't often give many football matches aside from the ones I attend my full attention, then again that's largely because in sport in general I'm a much keener viewer when I support one team, and as I've said many times, the England cricket team and the SWA are my favouroite sports teams.
I've got like a million posts in the footy thread so it's not like I don't follow it but I think it would be fair to call cricket my favourite sport.
Similarly on this forum I know plenty of you follow footy, Aussie Rules, Rugby Union & League, Tennis and others, so would you call cricket your favourite sport?