I like the bent knee on the second pose makes him look more ready for action. I made you an edit to show some things that could help you.

Finally, someplace on this forum where i'd be of some actual help!

Look here:

the knee's little "spine" at the end is connected to the shin plates of the armor, so they would stick out when the knee is bent.
What is the green thing at the back of the knee? all that's back there is the black connective... Whatever you'd call it, lol... so that can be removed.
on the Varia suit upgrade, there is a little bit of a "spine" attached to the forearm at the elbow.
finally, also on the Varia suit, the inside of the thighs keeps the lighter, yellow color of the standard power suit.
Everything else looks fine.
