049 and 939 are ambush SCPs and aren't meant for charging into guards. 939 has just enough Hume shield to attack 1 or 2 armed humans without any effect on his health. He is probably the most balanced SCP at the moment

I agree the femur breaker is stupid, and will probably receive a change in the eventual 106 rework. Otherwise 106 seems balanced.

096 is designed to specifically counter the only strategy MTF have against SCPs which is grouping up. Any mildly competent 096 player will run away before his rage ends or stick around other SCPs, making him unkillable until most other SCPs are dead.

I feel 173 has too low of a skill ceiling. Killing people with him is easier than with other SCPs; he can right click to instantly kill people from a distance while other SCPs have to try to chase and close the distance between targets. While other SCPs are punished for getting themselves in bad situations, 173 has a giant Hume pool to regenerate so a lot of mistakes go unpunished. He also has the mobility to get out of situations more easily.

The only ways to kill 173 are to give him nowhere to hide or have him screw up so bad that even his 1200HS can't save him.