My opinion - I would spray PB Blaster down in there and let it sit for a day or so. Next I would make sure I have a good spark plug socket (American, German, or Taiwanese made, no shit Chyna stuff that looks shiny). I would then put a solid extension on it (non-wobble) and I would hit it with an impact with a few ra-tat-tat's.
Why? This is a breakaway torque issue. You want to hit very brief high torque hits to break it loose. Your other alternative is to put a big bar on it, but then that's a last ditch for me. You want the head cold in my opinion.
In the off chance that you strip the thread, you'll need to Time-sert.
Let's go to the solution. People say anti-seize, lube, ... . The issue is that no one cleans the lands and the threads when they remove the plugs. The lands and threads are always dirty. I clean them with a grab tool, a 2"x2" torn piece of paper towel sprayed with brake clean. Tear a bunch of pieces of paper, and use them one by one until they are clean. Clean the lands and the threads. If you are a gun buff, you can use gun cleaning copper round brushes. On a plug change you'll spend 10-15 minutes cleaning everything. It's worth it. Now when the plugs go in clean and are torqued, they'll come back out.
Good luck.