Toyota or ford used trucks which is more reliable and better on gas? Opinions?

Well, smaller trucks usually do better on fuel than bigger trucks either way.

Toyota usually has fairly reliable vehicles all around.

Ford trucks are really the only thing they make I can honestly say I'd ever consider buying.

Problem with trucks is that you really want to know how they were used, how they were maintained, etc, etc, etc.

For example, if it was a truck used to going muddin', or otherwise as a toy I'd keep a distance from it.

Hunting trucks are similar.

Hauling trucks aren't as bad, but you certainly want to look at the transmission.

A USED truck is a USED truck. The reliability and fuel mileage on ANY used vehicle depends mostly on how the truck was serviced and maintained by the previous owner. It's nearly impossible to say WHICH used truck is going to be a better choice.