I've made gobs of AN lines and several hydroboost lines.
Some AN "secrets": Lube every fitting when you assemble it, every time. When you fit the collar to the line before you assemble the fitting, the collars are threaded BACKWARDS. I use a socket in my drill driver to spin the fittings on in reverse. This was a game changer. Even by hand, it is so much easier that fighting them. Aluminum adjustable wrenches are handy. Not all brands use the same sizes.
Hydroboost (PTFE core lines) aren't too difficult. Make your cuts cleanly and go slow. You'll have a much better time.
We currently have AN fittings on a TH350, TH400, and 4L80e. The later 4L80 needs a special fitting in one of them. If you look it up, it's obvious. The 4L60 uses the same fittings as the TH350/TH400.
I like the fittings that use a copper or aluminum crush washer instead of an o-ring. But that's just my thing. It don't think OEM had either.
BIG TIME IMPORTANT NOTE: HAND TIGHT ONLY! IF YOU ARE WORRIED ABOUT LEAKAGE, USE THREAD SEALER!
I snapped a good name-brand fitting off in my transmission two weeks before a race. Thankfully I was able to use a left handed drill bit and a lot of grease to drill it out. DO NOT DUMB LIKE ME.
EDIT: I like Evil Energy's AN kits. I've had good luck with them and they're very high quality for the price.