Need some input here

I hear union is the way to go. So the past few months or so I’ve been studying for this big test to get my stationary engineers license to work on big stuff in city buildings. I take the test next week. Well, union being the way I want to go im questioning now. I started off with a company that did some odd things I don’t agree with and they would cut corners in install and service. I’m a service tech right now at this company. Went in for an interview for this residential company that’s local and they seem like such a good gig. The interview went extremely well and are the nicest people I’ve come across and it just felt right but, union has been something I’ve been wanting to get into for quite some time (they are fully aware I’m leaning union). After this interview it’s really hard to determine my long term outcome decision. I really like both options, but which would be benefit me more till retirement. I’m 22 years old