Welcome to THR- hope you enjoy your stay.
There seems to be a majority of 870 fanciers here, for the obvious reason (more 870s have been sold since 1950 than any of the other makes/models). Of course, there is no reason to allow a mere 55 year record of unparalled reliability sway you one way or another 8^).
Even so, as I type this there sits at my left knee one of those FN Police Shotguns you mentioned liking. As a character-building experience I decided to buy one a while back and wring it out to see how it did. So far I haven't been able to find anything to criticize in a major way. You can see the review (so far) at
http://www.thehighroad.org/showthread.php?t=170316 . I wouldn't feel I was giving you bad advice to say, if you've shouldered it and it fits right/feels good, you should get it as opposed to anything that doesn't feel as good to you. They are good shotguns, just a Winchester 1300/Defender rebadged with FNH's name, and the package is a good deal IMO- long as the price is right. Mine was $265 out the door IIRC ($230 for the gun plus $20 shipping plus $15 transfer), if that helps.
No matter what you decide to get, remember that the gun itself is an inanimate object- it is up to you to make yourself into a capable and safe shooter. Work hard at it, and stay safe,
lpl/nc