Dogs On Acid - current nicest sounding vst synths
here's a thread i started on a dnb production forum about really nice sounding vst synths, it got some cool replies. synth squad is definitely on my list as well.
for features NI stuff is hard to beat, but for pleasant sound (to my ears at least) there are a lot of better choices. and of course dont forget about the nice free vst synths out there, some of them give the commercial synths a serious run for their money. personally i really like TAL elek7ro and Asynth.