Frankly, it will not make much of difference. See which one fit your boot best and have the most comfortable straps. Maybe check for features that you want, if any (canting, zero forward lean, erc.).
Weight does not matter.
Good advice, but I think that last line needs a little explanation. How does weight not matter? Pick up a pair of Technine bindings and then a pair of Burton Diodes and I know which one you"ll buy, even if they both had the same features.
To OP, I'm glad to hear that someone on here isn't thrilled with Union bindings. Despite all the love thrown at them, they look like toys to me, and about as durable. I switched this season to Burton Reflex from Salomon, but have yet to ride them, FYI.