The bit I use most often is a 1/4 up spiral. Second would be the same in 3/8. This is for cutting out MDF/plywood/hardwood parts on my CNC router.
A compression spiral would probably be better but I'm too cheap to buy one.
V bits are useful for sign work, lettering, and 2.5D carving. Ball end bits are great for carving work as well.
Not sure about the suggestion for bits with bearings I don't see this would be useful for a CNC, more for a router table or free-hand routing.
The post that asked about what you intend to cut was right on target, that will determine the best bit selection.
Since you're just starting out, my suggestion would be to buy a couple pieces of MDF and if there's a Harbor Freight store near you go buy some cheap bits there. The sell 1/4 spirals
$7 for 3 They're HSS not carbide and don't make the cleanest cuts but are great for experimenting, no great loss if you snap a bit. I don't see it on the site but in my local store they also had a set of 5 1/4" bits for under $10 that included a V bit and ball nose bit.