Okay..... You said BEST, not cheapest.
To me "Best" would be Accurate & Repeatable results.
"Best" would also include ease of use / setup along with the process being accomplished in a timely manner.
I have annealed hundreds of various cases using Tempilaq.
I feel that is an accurate method, but slow.
It also requires an additional cleaning operation.
So.... after a surprising xmas bonus, I took the huge plunge and purchased the AMP Mark II Annealer.
This has to be the easiest to use product I think I have ever taken out of a box and plugged in.
A .308 case takes under 3 seconds. A .45 Raptor takes less than 2 seconds.
I view annealing as a serious undertaking due to the risks involved.
If you don't get the case up to the correct temp, you have wasted your time.
If you get it too hot, you have ruined the case. This could spell trouble for the shooter and anyone else near by.
Have fun and be safe!