They made the s10 in a quad cab for a few years before the Colorado came out, so you could probably find one for a decent price. They were essentially the same for over 10 years and had the 4.3L which is uber reliable.
The dakotas were redesigned for 04 or 05, I can't remember which, but would definitely have the most room of all the 'small' trucks, and its the only with with an available v8. On the flip side, its a Dodge, so quality can be a bit iffy, but who am I to say, I drive a Jeep.
The Tacoma double cab would be a solid choice, but they're expensive enough that unless you found one with higher mileage you likely wouldn't lower your payments at all. Same story with the Tundra as that didn't come in a true double cab until 04 or somewhere around there.
The Nissan Frontier has actually had the crew cab around longer than any of the other small trucks. They redesigned for 02, but the ones prevous to that are nice as well. They have a 3.3L which is a higly regarded engine, but its going to be smaller on the inside than options like the dakota.
Sort of a lot of information, but if it were me I'd probably look for an S-10 as it'd be you best bet in terms of price and reliability.