To add to it I'll say that when I mean the I4 was smooth, I mean ahead of any other engines in the other vehicles, including the brand new rangers. The I4 in the ranger had horrid vibrations and the 3.0L V6 in the Ranger along with the I5 in the Colorado was in the same boat. This was whether new or used.
Also the 5 speed automatic in the ranger is really worse than the 4 speed. I was expecting it to be pretty good, but I was sorely disappointed. When you put down the pedal it drops one gear, and goes about 3 seconds before dropping 1-2 more gears. This causes two rather unsettling lunges in the vehicle, unless you're doing the I4, in which case it feels like you're hardly speeding up at all.
The Tacoma I tested was alright inside, and I'm sure everyone has a preference, but it wasn't anything special to me. The seats were softer than the competition, that was about it. Everything else was pretty much the same. Oh, and the suspension was a little softer than the Ranger, but not as good as the Colorado.
Plus do to a combination of market and bias the money into a well equipped Ranger barely nets a spartan Tacoma. One ranger was going for 10k and had just 40k miles, the 3.0L V6, Cruise, power windows, locks etc. The Tacoma was $200 shy of 10k but had 72k miles, a V6, no cruise, no power anything. I passed right over it. That's just stupid.
And even at a 3-4 mpg difference, on a tank of gas thats 60 miles you didn't get. *Every* tank of gas. Fuel efficiency is very important especially if most of the time you aren't using the engine to its maximum potential.
Either way my opinion still stands, all things considered, an I4 Colorado felt the best of all the ones I tested. Though I feel a Ranger is still a better deal.