I just took the plunge to buy EZdrummer 2.  I never realized how cool the features were in v2, and I got a sweet deal at Time+Space for it (97 Euros using a 10% customer loyalty coupon). 
 
With the promotion, I can pick a free EZX expansion.  What are your favorites?  Which do you recommend and which should I avoid?
 
I'm mostly into Pop, Rock, and Folk.  No metal for me. 
 
Unfortunately, I didn't get this in time to buy in on the additional sweet deal for the Rock! EZX.  Boo.

I don't have many, but from what I do have, Rock! is very good. Southern Soul is on my list to purchase, just waiting on a sale.

The DW Kit in EZD2 or Rock! are my go to kits for EZD.

Agree that ROCK! is pretty good. Progressive is excellent. Indie Folk is groovy. And as mentioned Southern Soul is top notch.

If you are into folk you would love the Indie Folk EZX. Listen to the demos that will help you out
https://www.toontrack.com/product/indie-folk-ezx/
 
The Pop EZX has 10 different kits and some are very nice rock kits. It would get you a bunch of good kits fast.
https://www.toontrack.com/product/pop-ezx/
You have some good rock kits that came with EZ D2.

Nashville, the EZD2 modern kit, ROCK!...all very good and very useful.

But nearest and dearest to my demented mind...Twisted...not for the faint of heart.

Southern Soul, Progressive, The Classic get lots of use here.

I think the best bang for the buck is the hip hop , and don't laugth ....i own Claustro , percussion , twested , indi , pop , electro , all are great , i really like indi ussually for acoustic , the thing they did with hip hop is that you such a variety of sources it's ridiculous (check the product pages and samples liste)
 from acoustic to electro , from vunil bacground noise to cool fx , ALL you need to spice up any Main ryhtm ...
 
The cool BF surptise i had ... really i don't do at all this boom bam stuff , but it's not vulgarous like a NI maschine kit , and way more loaded that XLN , witch gives you like one or 2 snares and kikc per bank !!! and varies sounds with FX and triggers ..... (not sayijng xln is less good , in a lot of arae it's better and i use it more , but for the number of spounds you get per packs , EZ is a better value) ....i might do a video on it since i struglled to find some on YouTube about it ....

Zo
I think the best bang for the buck is the hip hop , and don't laugth ....i own Claustro , percussion , twested , indi , pop , electro , all are great , i really like indi ussually for acoustic , the thing they did with hip hop is that you such a variety of sources it's ridiculous (check the product pages and samples liste)
 from acoustic to electro , from vunil bacground noise to cool fx , ALL you need to spice up any Main ryhtm ...
 
The cool BF surptise i had ... really i don't do at all this boom bam stuff , but it's not vulgarous like a NI maschine kit , and way more loaded that XLN , witch gives you like one or 2 snares and kikc per bank !!! and varies sounds with FX and triggers ..... (not sayijng xln is less good , in a lot of arae it's better and i use it more , but for the number of spounds you get per packs , EZ is a better value) ....i might do a video on it since i struglled to find some on YouTube about it ....

I usually would ignore than one but the demos are quite impressive and not just for hip hop.

Yep be sure to check the sample list ....i have some redundancy with some of my electro pack ....but they treated those and the producer doing it is not one those trap wanna be producer ...if yo know what i mean ...i used to layer drums on my own for a while now ... and i buy a mot of dry kits just for that purpose....the job they done is serious, classy and versatyle ....my only complaint is as usual those lack of control of soundqèans those fx that we have not enoght controls....

Thanks for the suggestions so far.  More are welcome.
 
I'm leaning toward the Southern Soul but I'll give an eye out for the Hip Hop.  Those aren't in the sale but they can be the free option.
 
I might pick up another kit or two while their on sale as well.