Man, you just opened a can of worms.....
Of the two mentioned, I'd go with the 26" job, since you have the 28" already.
But there's little that can be done with one and not the other, unless one has tubes and the other does not.
For quail, woodcock,grouse and other smaller birds taken close, a shorter barrel may handle better for a quick swing. OTOH, in a dove field or after NoDak ringnecks, alonger barrel is generally preferred.
Barrels on bird guns here run 21" to 30", and each has something it does very well and something it doesn't do as well as one on the opposite end of the length spectrum.
WEG for all around would be something like 23", but a better choice would be two barrels, a long one for where a little more inertia in the swing's a good thing and a short one for speed.
HTH...