I've owned a Painkiller, Warpig, Nailbomb, and Aftermath.
For modern metal the Nailbomb was right there. I liked the Warpig because it was just so ridiculous in the low end and it came out in the mix pretty well but it doesn't stay clean for any kinda of clean channel unless you really lower the pickup but that takes away from the high gain channels.
Anyway the Nailbomb is just perfect in my opinion, can't beat it.