If you can only take one of the two upgrades, which would it be and why? Assume that you've only got discardable munitions for this purpose, no modifications.
Personally I'm never sure - EM is guaranteed to work, from minute 1, whilst Crane needs a condition to be fulfilled - but EM only ever gets one use where Crane can be used more than once.
Equally, EM gets one use PER item, where Crane only ever gets one guaranteed.
I guess the answer is that it depends on the build - with multiple munitions, you're probably better off with EM, with only 1, I think I swing to Crane.
What about everyone else?