I have a sealed old-school kind of oil can that has a cover and stays nice and clean. Whenever I have red cam lube, green assembly lube, STP, thick oil, I drain it into that oil can for mains, rods, and cam bearings. When it's low, I add a little 20w50 or straight 30 weight, whatever I have around. It's convenient for bearings in the can, and the key is, with the cover it stays super clean. I would generally call it 20w50 Penngrade if I had to pick what was in the can LOL
For threads I use whatever the company told me in the way they tell me. However, exhaust bolts always get antiseize, and stock main and rods get ARP lube, other things like intake bolts, etc, just get something to not go in dry, often the "magic oil can", except aluminum heads which get antiseize
For pistons and rings, I don't do much, wipe the cylinder with oil, usually some clean 5w20 or 10w30 I have laying around. I also wash the bores ridiculously and agree ATF works real well, but for some reason I usually just go soap and water, and some oil based spray with lint free paper towels. I use the same for lifter bores and just slather it with my fingers.
For flat tappet cams, I like black paste type cam lube. My favorite is Erson, but it's a bit tough to find sometime, not sure it's any different, but seems more sticky. I also use Driven brand paste I did a test last year, coated 3 lobes, 1 black paste, 1 red Comp and 1 green Sealed Power. Goal was to wait a week and see which lasted the longest in a "completed motor" this was on the bench
2 hrs later, the red and green was completely gone.....the paste stayed put. I didn't even make it a day, never mind a week. The red Comp cams and green Sealed power sticky lube goes in the magic oil can now, to me it's just STP LOL