I've never shot an SKB but Browning has been in business for 100 years not so for SKB, who recently filed bankrupcy, that's gotta tell you something, I've got a BT99 every time I pull the trigger it goes bang.
Two completely different setups. The SKB can be had in a combo. Lots of options. Unsingle and double barrels are nice to have. You can do doubles no problem. The 99 will give you trouble on the doubles field.
I have a BT99 and love it. Like Warren says, every time it goes bang. But I like how the unsingles feel when I mount them. They feel like the have a more natural look. As I am dirt poor I was looking for the least expensive combo gun for an unsingle and o/u so I can do doubles too. I found SKB to be more so in the price range along with a few Berettas.
I think that is more where your decision would lay. Also I would try and shoulder both if not fire them. I did shoulder an SKB and I didn't like how it shut. Too quiet. I love hearing my 99 snap shut ready for the bird.