I like the '78-'79 Bronco. The early Broncs are cool too, if you get the automatic or convert the column shift to floor shift. I think the Blazer is more off-roadable due to its simple suspension and better drivetrain. Blazers are easier to work on and parts are much cheaper and easier to find than any kind of Ford parts. One thing that is so great about Blazers and Chevy trucks is their parts interchangeability. You can put just about any engine, transmission, transfer case and axle from most '73-'87 ('91 for Blazers, Suburbans and one tons) under most any other truck from the same era without too many modifications. That just isn't going to happen with a Ford because they changed stuff up too often. Maybe they employed too many engineers; I don't know.
Also, you can find Blazers dirt cheap (unless they're in perfect condition). Any Bronco from '66-'79 is going to cost you two to three times the cost of a Blazer at least, if you can even find one. One thing the Broncos had going for them is the crossover steering. It works a lot better than the GM steering design. Also the coil springs usually give a more controlled ride than the Blazer's leaves. This is why Blazers only cost about $500 to put an aftermarket lift on vs. $1000 for the Bronco. Now I'm just talking about the solid axle Bronco. The TTB is a whole different story. Desert guys love them for going fast, but for normal trails and daily driving, most people agree that the TTB sucks. It handles bad and wears tires out quickly if everything isn't in tip-top shape.
Finally, let's not forget about the good ol' small block Chevy engine. You probably see about one hundred 350 Chevies in custom builds for every one 302 Ford. There are good reasons for that: power, dependability, ease of maintenance and modification, and price. About the only advantage a Ford engine has over the SBC is that the distributor is in the front where you can get to it easier.
All that being said, I still think the early Broncos and solid axle fullsize Broncos are good trucks. I wouldn't mind having one. Their bodies are a lot less prone to rust than '73-'80 Blazers. You can find TTB Broncos dirt cheap too. If going fast and jumping is your thing, they may be the way to go.