Nice topic, Jeff. I have not loaded the most recent sample based instruments such as Cinematic Lights, Deep Flight One, or Lead Architect. Although I do plan on loading Sub Zero Bass.
I really like Impact a lot! Not as a complete drum replacement instrument, but with some going through Studio One's sample library, there are some exceptional bundled sounds. You can layer them, and create your own very detailed drum kits, and percussion kits on the fly.
Presence has bailed me out quite a bit on some really sweet horns, and strings. Bass as well, now that I think of it.
Sample One, is a blessing if you want to sample your own instruments. Sometimes I'm on the go, traveling or even in the backyard. I've sampled some instruments, from classical and acoustic guitars, as well as my bass guitar. With Studio One, its so ridiculously automatic entering notes with its auto-record feature. A far cry from when I used to sample sounds in the 90's with E-Mu, Akai, Kurzweil, and Ensoniq samplers (I still have some of them). Looping those samples was always something of a pain. Now its effortless. Sometimes I won't use the samples from Sample One, but use it as a fill-in, because its just easy to do, and I dont lose the idea. Anyway, sample One is a gem!
Mojito, I dont have much use for, but Mai Tai is a very attractive sounding synth. Sometimes it needs to go through something like a preamp to give it more balls, but it has some wonderful analog like filters. Does it compare with some other synths with punch? Not really, but again, you can get some magic when the vibe is right. Im also big fan of blending sounds anyway.
On a whole, you get back what you put in. I use other libraries from just a few other parties, but many a time, I'm often thankful for what sits in Studio One for added support. I do advise getting just a few other instruments that may inspire you. Especially when orchestral sounds are used exclusively. Naturally, no DAW library is going to compete with a dedicated sound library from a third party. That's not their job, but Studio One, Logic, Cubase and some others do a nice job of providing very musical sounds, synths and instruments. Studio One certainly does. It's just (thankfully) worth digging for. That leaves less chance of having some cookie cutter resemblance you hear from some other song.
Something can be said for the new sample instruments I mentioned above. Sounds can be combined and varied easily. I just would rather avoid them, and build from scratch. I understand that's not everyone. Still, there are some nice atmospheres that can be explored. If that promotes some feel or melody from that, then hay... that's a good thing. Samples can often do well when blended, so its best to never take a sound on face value.
Sometimes I hear a complaint from a newbie about how bad a library is. Honestly, I have to laugh because that person is just not ready to go deep enough, or expects some kind of instant gratification. I'm also from the 30% inspiration, and 70% perspiration bunch. ; )
If one were using orchestral sounds, what's there to stop that someone from opening Impact, dropping a few tympani, or vibraphone sounds on it to create some added textures? No rules are good.