Wingmaster. Preferably an older one. Never buy another shotgun again.
None. New 870's are garbage. Buy an old wingmaster or find another brand.
On a side note, you're the first person I've heard of hunting geese that only wants a 3" action. There are high fliers I've nailed with 3 1/2" that just wouldn't come to our spread and calls. I know I couldn't have made contact with 3".
Brownings BPS is the top of the line pump gun at the moment IMO.
The BBs coming out of the 3.5" shell are travelling faster so you get increased effective range.



























