Med 2 + Kingdoms is one of my all time favourites for sure, Broken Crescent mod is awesome, high quality mod with a fantastic setting. Third Age Total War is also fantastic quality and a must for anyone that likes The Lord of the Rings. Stainless Steel is pretty good for the vast size although IMO it also lacked in focus and detail because of that, still a good mod. Call of Warhammer is good but I found it to always be unstable and buggy, relying on too many scripts and scripted events to make things work, but if you like or have ever liked Warhammer at all you will have fun with this one.
That being said, they are all honestly good now, they all have good parts and the choice of eras is nice. They fixed Rome 2 and I also really enjoyed Attila, they're both quite different from the other games in the way things like army recruitment is handled, but I liked that. They're also the newest and look awesome, after having played the life out of the older games I tired of them and only really play Rome 2, Shogun 2 or Attila now when I want some TW fun.
Last of all, I can't believe you've never tried a TW game, hope you enjoy!.