I think 20moa is about average, and what most shooters want/use. I wouldn't bother with 5 or 10. Zero if you don't want elevation or 20moa if you do. That scope has plenty of elevation.

Seekins are good. They are about a hundred dollars. They also have a recoil lug (not that a 204 needs it).
A little cheaper are the EGW. They have a regular & heavy duty, either would work.
On the high-end you have Badger at $150+/- I think they are good but necessarily worth the extra cash.
I have own all three...
Ken Farrell is probably the nicest you can buy. I installed one for a friend and it's great.

Don't skimp on the rings!!!