What are the best/most usefull skills for crews to obtain and in which order?
I usually go for…

1. "Summarize Experience": Crew get +20% Exp
2. "Master Gunner" (for Ace crews): +10% faster reloading when driving certain tank
3. "Aim at Weakness": Chance to penetrate/destroy enemy modules +10%
4. "Rational Impact": -10% incoming damage

I'm not sure about 5, 6, 7,etc.. or if those skills listed above are useful early on, any ideas?

Note: I have Ace Crews for T-44/T-34-100, T110E5/XM815GM and soon Rhm-Borsig WT/WT auf Pz4