Re: Who to choose?
My advice- vote honestly. You can never be happy voting for the lesser of 2 evils when the one you see as right has to be abandoned. I say this as someone who voted UKIP previously (I know your leaning the other way) and it might make you unpopular or people might try to blame you for not tactically supporting Satan instead of Beelzebub but they are the ones lying to themselves.
You are in a better position than we were in, none of the mainstream parties wanted brexit as an option and if you still count the libs as a main party they are the lone voice to do what you want. But this is a general election and brexit isnt the only policy so be sure it is what you want.
Simply people complain about there only being 2 parties and then tactically vote for one of those 2 parties. They can never be happy and never be satisfied with the result they are always against the government and moan the gov doesnt represent the people or listen. Vote honestly and win or lose you know you did right. And even though UKIP lost the last general election they still won.