The trend of jamming social features into everything isn't really very beneficial to the end user. Generally they only show you what's popular rather than what's good, and are too prone to abuse. If I left it up to society to decide what was good, I'd be listening to Kanye West and watching the Kardashians. In the case of FTB, that would probably be Infinity, which is way too big for my taste and runs poorly for me anyway.
FTB only has so many packs. And unless you're playing HQM then there's really not much difference anyway other than the mod selection. Each has a description of what sort of theme it's about, and there's a list of mods, which should all be a pretty good indication of whether it suits your fancy.