This looks like an older thread but I’ll throw my two cents in here anyway. An up cutting bit will clear chips easier, but is not a good choice for plywood as it will tend to tear out the thin veneer coating. A down cutting bit is a better choice, but is also forcing the chips “down” into the work, and you can actually start a fire (quite literally) drilling out holes with a down cutting bit, so be careful.
What I found does a very nice job is a two flute bit. I’m especially fond of the Amana 2 flute as it allows plunging. Not all two flute bits have the cutters going to the center or even if they do the cutters tend to be flat or straight. This is not good for plunging. You need a cutter that is slightly angled, so the outside edges hit first, and then the rest of the cutter clears the chips kind of like a drill bit.
Lastly, better software will allow you to “ramp” into the work which makes it easier for the bit to plunge into the work. This is not possible with 2.5D work or what most other people call 3D work. The amana cutter mentioned is $15 or so vs $30 or so for a downcut bit.