I think any pop, rock 80's would be nice we all sing alone to that,
Would be great to see, hear and be able to communicate with passing trucks and also have and see Police Scanners within the trucks :)
Also to be able to listen to our own local (e.g: Brisbane, AU) radio station from where-ever we are playing :)
I think it's impossible, at least for me, to name just one favorite trucking song genre. If I'd have to choose, I'd say Pop rock 80's, Pop rock '00's, Hard Rock, Electronic, even a minor portion of dubstep, some chillout, a very small portion of hip hop, most forms of reggae, some drum 'n bass, metal, a bit of country.
Even some blues and jazz, because I like them, although for trucking it's less interesting. Swing and classical is good too most of the times.
What this means is that I chose 'Other' as the option, even though I prefer most of the listed choices, but I didn't want to name just one, because none of them really stood out as 'the' choice for me.
Perhaps then, my opinion isn't really interesting for you, because I can't push towards one genre... most of them are awesome!
Pop Rock '80 and Country music!!!