Cash. Always cash, whether you do it, or hire it out.
When our water heater failed, I took cash and did it myself (with a much better/more efficient water heater, well within budget)
When our central AC failed, we let them arrange the replacement, as I wasn't going to DIY - holy crap. Took WEEKS. In July. In Texas. And the guy who set up the new one didn't even top it off with refrigerant or insulate anything. It was just CUT/YANK/SOLDER/RUN - yep, he vented the old CFCs to atmosphere instead of capturing. Old expensive CFCs too. Sure, the new unit came with the right HCFCs, but you to actually VERIFY once it is running for ~15 minutes.
Oh, and they never pulled a permit from the city until I had complained for MONTHS. I think the tipping point was when the home warranty company wanted us to renew in October, and my answer always was "When you get those incompetents to finish the last job and pull a permit on the AC installation from July, we can talk about it"
I should have taken the check, and hired someone competent.