Havn't had a great sub but Subway is edible and makes up a few lunches per month for me.

Quiznos I didn't really like, but they are fairly new in Australia and will have to try them again one day.

I think subs are generally healthy. Subway keeps their stores clean, and the food is fresh. I've always been impressed with the hygiene shown by Subway staff (even down to them changing gloves between subs, and having seperate cashiers).

Much better than a pie or burger or similar health wise methinks.