The most classic Warhammer Fantasy Battles system I'd recommend is the 3rd edition. Maybe not balanced, but has tons of character.
6th/7th ed WFB was about balanced. The books that went over the top were, I think, 7th ed Skaven and DE. Some problematic individual units in other books too.
Then again if you like 6th/7th ed, Mantic's KoW is a very good alternative. I strongly feel it has the same spirit, but is one step simpler and plays considerably faster. I fully concur with what jtrowell wrote above. You have basically three human armies, and while none of them is 100% the WHFB Empire list, they provide very nice uses for an Empire collection. And there's the KoW Historical, which gives even more and extremely fluffy options for a classic Empire army with the Swiss/Landsknecht looks, like the Holy Roman Empire list. You can use those in the fantasy version too, and indeed the Historical lists do contain some fantasy elements, like an Ogre style unit for most armies, HRE included.
8th ed is still around in clubs and played by many with minimal changes. Personally, I found it bland and unbalanced, and especially the Empire suffered from some of the characterful units being weak. Like Handgunners and Mortar. (Then again Empire was quite tough during the 1.5 years after the BRB release but before the new AB, i.e. 7th ed AB with 8th ed rules.)
T9A is more than fine-tuned 8th ed, it's balanced but also a kind of competitive version, where you can fine-tune and buff your units more than in the 8th. Then again you have the 2016 0.9-1.1 versions (available somewhere) which are re-balanced 8th ed. But that system is also evolving into something intentionally different some time later this year, with the advent of the 2.0.
If you hated AoS when it came out, you might want to check where it stand nowadays, with the General's Handbook and points system. Still not everybody's cake (what is?), but I hear many oldtimer WHFB players who absolutely hated the first 4-pager rules have now found the system rewarding. Still sort of beer & pretzels, but not a bring-a-monster-and-beat-the-other-army kind of a kids' game anymore.
In the end, your group of gaming friends will help you to decide where to go. It's a rich era to play Fantasy Battles, only somewhat confused without a single dominant game system.
-Z