DON'T try for deskwork or it will be ALL you do!!!!
ANY MOS once you get up in the ranks will involve deskwork. Maybe not at start but as you start to become a "manager" (a Non-commissioned Officer), you will!!
Pick something which interests you. ALSO look for something which will train you in something you could do AFTER the Army. Combat arms sounds fun but is very physically demanding and doesn't pay as much as the NFL. But you Could be just as beat up in the end. (those guys retire before 40yrs old?)
I don't know that you can pick ANY job, but ask at MEPS what's open. Don't just settle on one or two.
I went Signal because I asked for "big bonus and high tech". If there is a bonus offered it means not anyone can do it- and generally people do it, get skills, then leave the Army fairly quickly.
You can work on electronics systems, you can repair vehicles or helicopters,
-truck driver and cook and mechanics work long long hours,
-there are JAG (legal assistants)
-MUSIC (you can get paid to play in the band! but you have to already know how to play and audition)
-medical assistant jobs (NOT just combat medic!)
-all kinds of other jobs...
You never know, just ask!
Be Proud of what you do- and do it Well! ~me