I think that for most guys especially newbies, that thimble & crimp or thimble & knot are the most reliable and repeatable terminations.
Pony recommends the AG chain knot only for the hard fluorcarbon line, not for nylon. Even then, the leader must have knot sleeve protection. During my recent 3 Kings trip with Pony, the heaviest leader he used was ONLY 84lb flurocarbon!! He used the red knot sleeve and Chain Knot and I never saw any breakages while he and his mates caught plenty of biggies too! In fact the 84kg Bass on his iconic "Jigging in the Dayline" DVD was also caught using just 84lb FC!
The message to me is clear! If you must use soft nylon mono, then use heavy leader & protect the leader with thimble or hard tubing. The few reasons to use such heavy nylon is to preserve strenght at this critical knot or when jigging in tiger country. If you want to use hard FC, then you can reduce leader strenght but use leader sleeve and tie the Chain Knot. FC is well known for increased hits and now improved knot strenght.
You have to understand the huge pressures on the leader against the solid ring. Soft nylon will stretch, deform and lose a lot of its strenght making it susceptible to breaking under pressure. A harder FC leader just doesn't stretch!
Every busted leader is another 30+kg Kingi about to die and this should never be taken lightly.