Genre - orchestral/film, pop/contemporary, jazz
In order of importance (other than the DAW software):
1. Kontakt 4 (won't mention libraries here - too many)
2. SD 2
3. VSL
Kontakt is the single most important plugin in my setup. Almost all the sounds (90% or more) I use come from Kontakt libraries. My VSL is mainly for certain solo orchestral instruments (oboe, flute, classical guitar, soprano sax) - if my music calls for them. I also have Kong Audio but have not done too much Chinese music lately - so they are waiting to be used (I have a few Chinese pieces up my sleeve...). Absynth, FM8 etc are nice but not essential for me - I hardly use them at all. I have lots of other plugins but they sit around doing very little/nothing. Examples are Massive and Battery - never used them but they are there as part of Komplete.
For the mixing/mastering side of things, after upgrading to Sonar X1, I need few other extra plugins since the Prochannel in Sonar X1 has excellent EQ, compressor, and tube saturation. I won't consider them as additional plugins since they are integrated in Sonar X1 DAW environment. I still use some which can be important (but not absolute necessary, and in order of importance):
1. SPL TwinTube for certain tube saturation with a different colour than the one that comes with X1
2. Guitar Rig 4 if I'm using guitars (in fact almost always if I'm using guitars)
3. NuGen Audio Stereoizer 3 (quite crucial for certain solo instruments to expand their stereo field)
4. PX64 Percussion Strip (part of X1) - use that quite often.
5. Flux PureLimiter II - for touch ups at the end