It's more of a question of general fun of the build, how you play it, how often you need to use different consumables/utilities, change tactics etc.
3 pistol types rated by feat requirements:
chemical << energy << ballistic
as such you can easily pair chemical and energy with melee, basically doing both at the same time. ITS FUN. If you want to adapt your tactic endlessly -> this is it.
Chemical vs energy is picking regular vs crit attacks.
Whats best about energy is that it comes online before depot a. Chemical could too but good luck getting chemical pistol by then.
With both chemical&energy you dont need expose weakness. Its not just about free slot but rather you dont have to get in melee range ever. Unless its your choice. I found ballistic pistols quite limiting in that regard.
With ballistic pistols you want to always be in melee range.
You will find yourself switching to lazor/chemical often to deal with pesky resistant enemies. Eventually you will start to wonder why you didnt focus on those to begin with. And restart.
Crafting:
if you want chemical + melee, then you pair it with claws. Claws are fine without crafting, but you must craft your chemical wpn.
lazor + melee -> both are crit focused. With heavy duty there is an amazing lazor option so you can skip crafting that one(frees up feat too). Sadly - knife still needs to be crafted. You will likely craft lazor gun anyway due to tech gadget - mind you that crafting something better than unique lazor is going to be hard(from memory you need q155 lazor emiter to break even?)
ballistic + melee -> There are great unique guns, could skip crafting on those. Can go either crit or not, if you go no crit then grab a claw so you can skip crafting completely.
Im always there for you to explain what is fun vs not
laz0r + knife are most fun.