IMO, all non-heavy weapons are fairly well balanced against each other (if you disregard the blatant cheat mode that is plasma rifle's explosive fire mode).
The choice of a weapon type may determine the faction that you'll have to join, since min-maxing certain weapon types requires being a member of a specific faction.
I tested all the ranged weapon types in my full playthrough, and almost all of them had something going for them even in the endgame, with only xbows and harpoons falling off due to not having adequate endgame damage for their top models. Bows are slow and clunky, but have YUGE damage per hit and also very powerful berserker-only skills, shotguns and lasers are a great middle-of-the road weapons of choice (good damage, good rate of fire, decent hitbox detection once you get used to them, cheap ammo), and plasma is a more expensive but more powerful weapon of choice with extra damage mode vs mechs (and also another cheat mode fire type).
Melee 2h weapons are pure preference - any weapon type will perform well if you like the animations and "feels". Zerkers and outlaws get their picks of swords and axes, clerics get the 2h hammers.
1h vs 2h vs 1h+shield - pure preference again, everything is viable. Shield gives super-blocking and easy special move that stuns opponents, 2h gives larger aoe and more reliable stuns, pure 1h is middle-of-the road.
Also IMO, the game is heavily biased in favour of melee early on - you'll have to grind stats for a while to be able to equip the better ranged weapons than your starting bow, and the relative tankiness of earlier mobs makes the economical cost of killing them with ammunition quite exorbitant.
Midgame onwards you can specialise if you want, but in the endgame you will be proficient both in ranged and melee. However, the nature of endgame encounters makes ranged a superior choice - it's easier and faster to pick off multiple enemies from a distance, before switching to melee if any of them make it to you. Regardless, going pure melee in endgame is perfectly fine if you mastered the melee combat system.