With Giz on this one. Both are good, the 87 may have a slight edge due to ammo flexibility.
Some Police 87s have trouble with lighter loads. Use something heavier that a trap load in these and all should be well.
If I were to abandon all my 870s and put together a Semi auto "Serious" shotgun, in all likelyhood it would be on the 87 frame. Not likely to happen, tho.