I like LMT Onsrud bits. 
https://www.onsrud.com/articles/Router-Bits-for-the-Sign-Industry.asp
Sharbits have some cool kits, but they're definitely not cheap.  We bought this one a while back: 
https://openbuildspartstore.com/3d-sign-maker-deluxe-7-pc-cnc-bit-kit-v1/
We also use a couple of bits from this Chinese company: 
https://www.china-oyea.com/index.php?classid=413  
 500-9851 Routing bit D3/3-L60/20 1FL UC
 500-9858 Routing bit D6/6-L58/22 1FL UC
Mainly use those for PVC and the odd wood project.  They dull quickly but they're dirt cheap/disposable. 
What materials will you be cutting?
It can definitely get a bit overwhelming when you're first starting out and trying to find the right bits for a whole bunch of different materials.
I'd suggest finding a good distributor that is knowledgeable and just tell them you want to cut X/Y/Z material and see what they recommend.   Buy one of each of a few different bits, test them out, then make sure to document feeds/speeds and keep those common bits in stock.