The Standing Order is good value as its a Wetherspoons. And it is very big inside.
Nearer to the station, Encore (24, old Rat and Parrot) is your typical pub-in-town-centre but not too big. More roomier ones on the on the way to the ground are Old Fat Cat and Tavern in The Town (16 & 17). These are pretty big but prices are higher than Standing Order. Saintforever seems to have designated them "Home" pubs - could be good or bad depending on ticket situation.
When you get past the high street and down towards St Marys itself, the pubs get smaller, more grotty and less welcoming.