Get the Kontakt Factory Library if you can. Lots of great, very usable stuff in there, especially in the strings and brass department.
I like the new piano libraries they dropped last year (Maverick, Grandeur).
Honestly, I’d recommend just grabbing a used copy of KOMPLETE 8 or 9 off eBay if you can find it. I got Komplete 8 for $200 a couple years ago, upgraded to 9 during the summer sale last year for $100, and just made the jump to 10Ult this year, all for way less than buying 10Ult outright. The synths and effects that come with KOMPLETE are just incredible (90% of my tracks are just Massive and Guitar Rig).