I have 2m ham and CB in my jeep. I have a dual band ham, CB, and GMRS in my tow rig.
I find ham to be the most useful on the highway and in the city. I also find it to be a more effective communications tool offroad than any of the other legal and pseudo legal communications platforms (see my comments about Rugged Radios below).
I don't hear much highway traffic on CB any more (except the high powered "skip monkeys"), but I use it on nearly every jeep run because CB is still the most common offroad communications platform (despite Midland's marketing push toward GMRS) and is required by many organized offroad events including all events organized/sanctioned by the California Four Wheel Drive Association . I do not see that situation changing anytime soon because so many people already have CB's, CB is inexpensive, and no license is required
I have yet to find anyone to talk to on GMRS channels on the highway, but there have been a few occasions when someone with GMRS would show up to a run and not be able to communicate with the rest of us who had ham or CB which required me to use my Baofeng handheld for that purpose Since I acquired my tow rig with GMRS, I have heard no traffic at all although I realize that some groups are now using GMRS . In my opinion, it is not yet universal enough to be useful for general communications. Maybe in 5+ years.
As far as Rugged Radios or "race radios" are concerned, they are units operating on the business frequencies supposedly under the auspices of an "umbrella" license granted to Rugged. This practice if of questionable legality, and just because Rugged Radios says it is okay doesn't make it so, all it means is that the FCC has not taken any action against the company or its customers. Frankly, I have never understood the allure of "race radios" because you can only talk to others using that frequency -typically only your own small group- which makes them next to useless for general communications n larger events and for emergency transmission purposes. Why not just pay the $15 for the ham test, spend a couple of hours studying, and be able to use VHF and UHF bands with accessibility to the world?
My two cents.
BTW -
Last year I did a month long overlanding trip in Mexico using ham for group communications. It worked perfectly even when we were separated by many miles and we were able to speak with others as we traveled for local road conditions, locations of military checkpoints, etc. There was substantial CB traffic, but it was primarily cab drivers, delivery vehicles and sometimes the police in small towns.
Two months ago we did a two week overlanding trip in NorCal, also using ham. Communications were reliable and we were able to make contact with locals who advised us of current fire conditions, closures, etc. which allowed us to alter our route as necessary without having to go out to the highway to get information. I heard some CB traffic, but not much.
CB, GMRS and race/business band radios would not have worked for us in those situations.