4.10s definitely get less mileage than 3.73s. So if you're looking at mileage then you might want to go with the 3.73s.
my general rule of thumb is to go with 4.10s for an automatic and 3.73s for manuals. I don't know if others follow that rule but it's what I've heard from a variety of people around where I live.
Strangely enough, I answer this question at least once a month. I put a link to an article on this very subject. changing the gears is going to cost $300 in parts alone, so you want to feel something for the money. forget the 3.73 gears. No kick for the money. you will feel something with 4.10, but I like 4.30s. 4.30 has a kick, and mileage is not effected as much as people say (maybe 1-2 mpg less) over stock. On my Ranger it improved around town. If you have hills in your town as mine does, it really helps. I only wish I put in the 4.56 now. as far as top speed goes, well how often do you drive 160, or 140, or 120? your top speed is going to be around 140 basic on engine rpm, but your ecu will limited you before then.