Shootem up 870, someday you need to make a trip down south to an area that still has dog hunting for deer. It is so much easier than man driving (which we occasionally do when we are temporarily out of dogs, or when hunting near a major road). I too like my 870, but I will forever be partial to my Browning A-5 "Sweet 16". I just cant find any good deer loads for 16 bores.
As far as rifles go, find what feels best that you can afford.