I love fix power scopes. The big pro is the fewer parts you have, the less that can potentially go wrong, the lighter it will be, and it will be optimized for its power, and has the potential to be brighter at its power than a variable at the same power. You get use to one sight picture and you never have to worry about it being at the wrong power when you pick it up. You know what you are going to get. They should be less money, but because of economies of scale, they rarely are that much cheaper. The con is, it's a fixed power, choose wisely.
A variable scope has no cons that you can't spend the money on to make go away. With that said, there's the con, quality/complexity costs more to make.
Since you are airgunning at under 50 yards at small targets a fixed 10x could work for you all around but if you're strictly target shooting you might want to jump up in power.