Best weapon perk depends somewhat on your targets and what special ammo (if any) you will be using.
Initially I would just look for something cheap which has similar (or better) ammo usage and higher damage/accuracy than your white weapon, as that is still an upgrade regardless of perk.
The reason you hear more about guns than melee weapons is just due to the lack of mods for them. They will only be as good as they are when you get them, and when first starting out that is great because they don't need ammo and you don't have the mods or educations to make guns favourable, and you're less likely to be attacking someone using any of the "added protection against melee" options.