I'm a big fan and user of PB Blaster and have about half a dozen cans sitting in my shop right now but when a part is really stuck hard, PB can't get into the joint like Kroil can.
I had a busted bolt in a torque tube and had soaked it for about a week with PB with no luck. I started with Kroil and it came loose in about a day. Kroil has better pentrating qualities and sometimes makes a difference.
Both products are well regarded in my shop.
BTW - are you using a good puller?