Then again, in the US it's very hard to focus your vote like this due to the two-party system. So... work on getting a better political system in place?
There are unions that behave badly, therefore unions as a concept is broken and should be abolished.
Funny enough that logic never applies to corporations. If some corporations behave badly, murdering people, overthrowing democratically elected governments, kidnapping children, well, that's just how it is, we can't abolish corporations, even regulating them is criticized.
Unions help the small guy though, so those are okay to trash.