When I first started producing tracks in the late 90s I had lots of different sound modules in the rack and keyboards on the shelf trying to access as many sounds as possible. It was a struggle to say the least to recall patches and volumes and have everything show up the way you left it. I'm sure every producer had their own methodology that worked for them. Now the modules are gone and all of my sounds are "in the box". In my main studio I have 2 keyboard controllers, One is 88 keys for playing piano parts and anything similar . The other is 49 keys and has a lighter touch which is great for organ, pads, drums, etc...
And there is virtually and endless landscape of sounds. Every producer has their favorites. Here are some of mine.:
I really like the cutting edge sounds of Keilwerth Avenger. For any song that has a modern vibe I can always find something. For orchestral sounds I use Miroslav Philharmonik. They sound great and they give you a really wide variety. Another plug-in I find very useful is Session Guitarist Strummed acoustic for Kontakt Player. My acoustic guitar playing is ok but this sounds great right out of the box. I just wish they had more patterns available. For drums I use Either Battery 4 or NI session drummer. However I've been hearing some great thins about IK Multimedia Modo Drums. I will have to check that out. For electric guitars I really like the Evolution series from Orange Tree Samples @OTSamples . I use Evolution Strawberry but the others are great as well.