Yes I prefer the med tank. Useful for :
- hit and run tactic
- med tank rush (why people never use this ??! Whith hotwire inside this is just deadly)
- defending via blocking/destroying incoming flame-tank/apc/buggy (especially efficient on under, field, wall).

I use med also because the enemy get less points when he destroy your tank. I've seen so many games where GDI lose just because of large number of destroyed unsupported mam...

Just attacking alone with a mam is so...