Zan, I'm biased as heck in this, but I prefer the 870. 40 years plus of glitchfree, heavy use will bias the heck out of most anyone.
The Nova may be an excellent weapon. The 870 has proven itself to be the standard against which all else are measured.
I shot the Geezer League yesterday at pGC as usual. Besides my 1988 era 870 TB, there was a 1959 WM, an early 60s TB,and a WM of unknown age. The early 60s TB has been owned by a trapshooter now truly ancient, who stated it's had over 100,000 rounds through it. New parts have been several stocks, and a Timney release trigger.
BTW, the 59 had me drooling, the most gorgeous wood I've ever seen on a field grade.
Get the 870, your great grandchildren will thank you. Then, if you still have a yen, buy a Nova, shoot them both, and sell the one you like the least or the one that glitches the most. I'll wager a flagon of mead the keeper will say 870 on it....