The REAL go-to build for mutants
Let me explain. I've come to the conclusion what this combination of mutations - maybe the best possible one for playing without any shenanigans.
So, you get a nice boost of stats for early game, second head what you can use early for faces, rank fangs, or even snail shells for dealing with Slog and also half immunity for all mental debuffs. Also nice bonuses like dazing on all melee hits, which will carry your melee fights and procs of No Cooldown with your sprint and Long Blade skills.
After that, you raise double-muscled to 9, triple jointed to 9, heightened quickness to 6. And that's it! On about level 20 (you will have all of this if you spend you spend one RA to both Triple-jointed and Double-muscled), a whooping amount of stats what will give you nice PV, DV, QN, without any spending of attribute points. So in the case of this character, you will have 27 dex/str just by hitting level 20. This will allow you to, for example, spend all your attribute points to INT to reliable have 29 int for Tinker III, while also having decent stats to deal with anything. Also, when you will be about level 30, this will getting just better. Or you can pick another calling and max your willpower, for example. Or Ego, this will work too. Or just put your RA only in Double-Muscled and max str for axes.
Another good thing in this mutations list - this is really flex setup, which can support almost any playstyle (yes, you can't really have Multiple Legs for ranged build with this, but if you really want to do a character who uses guns as a source of main damage you really better to just pick True Kin, they just better with guns than mutants). You can freely play without any defects and still have solid build, but also you can pick Tonic Allergy and have whatever 4 points mutation you like. Regeneration, Precognition, Electrical Generation, Wings, Stinger, Multiple Hands or even Light Manipulation, which also will synergize with Two Heads, so you will have this gish-like playstyle.
Here's specialised variations of this build:
You can also go Apostle with this one, but i think this version will be better because you can just boost your Ego by wearing two faces with two knollworm skulls and get Proselytize from Mechanimists
London style mainhand MWF dagger
More detailed on this one - you actually doesn't want to make Stinger your main weapon, because Stinger will attack even if you have Single Weapon Fighting on, so you just take longblade skills, some nice longblade and enjoying free procs of Stinger from Charge and Lunge all day. Also this can be Paralysing Stinger, but assuming what you will still have Daze and Stun from Double-Muscled, this is kinda wasted, Poisoning stinger solves all your problems with high AV enemies before you have access to vibro weapons, and also just a nice addition to your damage later on.
That's it, live and drink!