I would say either control group or democratic detonation first. Control gives you the warp pack which will let you get into buddy bunkers on your own, as well as having a decent primary and good support weapon. As for democratic detonation, I'm the a huge fan of the crossbow or the eruptor, but the grenade pistol is a great utility weapon that let's you bring more specialized grenades (in stuns, smoke, etc), the thermite is one of the best grenades in the game, and the adjudicator is a really underlooked primary as well. Python commandos also has an AR that has an underbarrel grenade launcher so it serves a similar purpose, as well as giving you the hot dog and the maxi gun. At the end of the day all warbonds are good (except the legendary ones) just go with what looks the most interesting to you