I'm a fan of the 12.5" Grizzly...hard to beat the barrel length and price combination. I then proceeded to do what some of you may think is foolish, but I spent around another $400 on it by sending it for some TLC from Casey at TacOrd. He smoothed out the internals, parkerized and painted it, and installed Wilson Tactical ghost rings, as well as replaced the foregrip. I then put a Knoxx SpecOps stock on it, a Mesa sidesaddle, and an aluminum follower (OK maybe more than $400 total...) so...
I wouldn't trade it for anything in the world. I love the simplicity and parts availability of the 870 platform. If I were doing it all over again, I may start with a better base model like a used wingmaster so I didn't need to have the internals cleaned up, but in the end, I got the short barrel and all metal internals for under $300. The short barrel from alone from other sources costs about the same.