I have only used Addictive Drums very briefly. It's a solid product and I'm sure you will be happy with it.
However for me SSD 4.0 is just the ultimate drum vst cos it comes with your mix-ready kits from previous versions, as well as kits that have been recorded dry which allows you to eq/compress etc to your hearts content. The sound quality of the samples is just fantastic and it's not a lie that the kits are mix-ready. I have used the 'cracky metal kit' in a mix, and all I did to it was use the loud maximizer on Ozone to get it a bit louder.
The platinum version of SSD 4 has over 100 kits - there is so much variety, and a different kit for every situation (including a few electronic kits). You are also able to load your own samples into the SSD player if you so desire.
Another positive for me is that you can create and load your own midi maps, so you don't have to stick to General Midi mapping if you don't want. SSD 4 seems to have its own mapping out the box, which I think is a bit dumb, it should have been set at default on general midi and then given you the option to edit.
Just go to Mr Slate's website, listen to some of the demos and youtube videos and I'm sure you will part with your cash asap ?
http://stevenslatedrums.com/
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Slate Digital customer support is also top notch. After I finished my download my license key wasn't appearing on my account for download. Mr Slate personally responded to my support ticket and sorted it out really quickly.
As far as EZDrummer is concerned, I wouldn't go near it. The basic version that just has the pop/rock kit is very one-dimensional. The drumkit from hell expansion which I had was over processed and barely usable. If you're going to go the Toontrack route, then go for Superior Drummer.