So I have around 56k as of now along with a few mercs: vassili, fragger (from free event), proxy. Should I buy nader or wait for red eye/other mercs (since getting another 50k will be complete hell HAHA)? I’m not too fond of smg’s cuz I became so used to semis/bursts now, but unloading explosives onto campers has been quite delightful (on my fragger).
Deciding on Buying a Merc
Either Nader or Fletcher fullfil that role, Nader is easier to use; so probably best as your first pick for explosive merc.
$$$ increase rates have been buffed again (first play/win bonus 250->500); so thats an additional 750 you can easily haul in everyday, should be possible to get 50k in 15-18h of gametime.
Kira is fun on any map besides Underground as long as the enemies don’t notice the “pillar of fire” that she calls down. The laser is a great area denial tool.
Sawbonez makes SMGs worth it.
Otherwise wait for a new character. You have the useful ones
It depends how you like to play. Arty or Kira are great at dealing with campers in certain situations and can be equipped with burst fire weapons. Skyhammer is another good one as his airstrike marker doubles as a small explosive grenade indoors.
All of those three will give you the ability to dish out ammo aswell, which people appreciate 
They all can be really fun, if you narrow it down to specific class I.e. medic I will give you a rundown of how the mercs in that class work.
Kira is definitely awesome against campers, plus she’s got a pretty unique playstyle with burst/semi rifles and fast movement. I can definitely recommend her. I also recommend that, whichever merc you decide you want, you try them out before you buy them.