I rode Unions for 3 years. They suck. My roommate rode them for 4. He's over them and will never go back. Hows that for personal and friend usage info?
"Sucks" isn't very informative, and it's also very subjective. If you don't like the toestraps, or feel that Unions have too little baseplate padding, why not just say that?
I am not a fan of K2 bindings. I think that the auto toestrap, hinged straps, and canted footbeds are overly engineered and just more stuff to have to fiddle with. I don't like rear-entry bindings, as in my experience it makes bindings less responsive. Tool-less adjustability is nice, but some of the solutions that I've seen make me wonder how durable they are.
None of that equates to a justifiable statement that one design/engineering approach is "better" than another. It just means that my understanding of a better solution is dictated by my experiences as a rider - as are yours.
Investing in the latest version of snowboarding fanboyism (which started 25 years ago as "Burton vs. Sims") is just so much bullshit. I don't care what gear you ride. I am curious about honest, insightful feedback about why gear has or hasn't worked for somebody. We are not defined as riders by the gear that we ride. We are defined by the stoke that we share. 90% rider, 10% board. ALWAYS.