Open hammer side by sides with British straight grip, splinter forend, and double triggers seem to fit me best (as do hammerless side locks). I also like the ability to check the status of the hammers without looking down at the gun. Double barrels and double triggers have the obvious advantage of instant choke selection.
Open hammer sxs's I have owned and since sold:
Abbot and Company. 12 ga. 2 1/2"
Armi San Marcos, 12 ga. 2 3/4"
Sanford and Laxton Practical Gun and Tool Makers, 16 ga., underlever 2 1/2"
Open hammer sxs's I still own:
Saxton, 20 ga. 2 1/2"
Husqvarna, 16 ga. 2 1/2"
Daudson, 12 ga. 2 3/4 - 3"
TOZ/Baikal 12 ga. 2 3/4"
TOZ/Baikal 16 ga. 2 3/4"
TOZ/Baikal 20 ga. 2 3/4"
Another Saxton would be almost impossible to find.
The Husqvarna is a favorite of mine because of the round action receiver. However, it is POW grip and accepts only up to 2 1/2" shells (not a limitation in my mind, but a showstopper for some folks).
The Daudson is virtually new and not half the gun the others are.
The Baikals are much better than one would expect. The 3 gauges are on properly scaled frames; they are reasonably well balanced; they lock up like vaults; they are well regulated and built strong without being as clunky as later Baikal models. On the negative side, they are all POW grips and birch stocks. This model was made in the late 1950's.
As you can see, there's only one in the lot that accepts 3" shells (and it's not one that I would recommend). None of these hammer guns are intended for steel shot. There are slugs, buckshot, and bird shot readily available in 2 3/4". The Huglu HRZ and the Pedersoli La Bohemienne are about the only 2 commonly available open hammer guns with screw-in chokes and 3" chambers.