If we are talking about the new models, I vote the trailBlazer. I've driven both of them (rentals for my company) for an extended period of time, and all of my co-workers preferred the Blazer as well.
These were '08 models, 4wd. The Explorer was the V6, the Blazer was the I6.
The Blazer had more headroom, had a more comfortable interior, had a smoother suspension, and was a more capable vehicle offroad. The Explorer was faster off the line, had a more firm suspension (sporty) so it handled better (plus the independent rear suspension), but was harsh when offroad at all.
Fuel mileage was comparable between the 2; unfortunately I cannot remember exactly what we got. Even then it wouldn't be comparable to real world numbers because of the amount of slow speed, offroad, and extended idle times that they were exposed to.
I do remember thinking that the Blazer's rear suspension was too soft. The interior of the Explorer got dirty quicker from dust, as if the doors or HVAC system was sealing or filtering properly.