VI really opens up mod potential - I've tried and love Hellenic, Napoleonic and just got Pike & Musket. I even made a mini-mod with the HTW Roman units and the VI Britain map for a "Britannia 43AD" campaign complete with numerous Brit tribes -- then went and killed my hard drive and lost the whole thing. Not very historic on the Romans, as I was still using hastati, triarii and principes, but it was fun (while it lasted, sob).

I've downloaded but still have to try BKB, XL and MedMod so can't comment on those yet. Mainly because I like mods to change the timeframe as much as anything. HTW was a real eye-opener - must reinstall it on the new machine someday.