The only one of your questions that can be given an answer that almost can't be disputed is engine life.

A ringed engine, given proper care, is almost impossible to destroy or wear out. The best of the ringed engines have a chrome plated cylinder bore. All Saito and many K&Bs have the chromed sleeve and ringed piston.

I just did an overhaul on a 30 year old Saito, all I had to replace was the piston ring, bearings, and the valve springs. That made it essentially a brand new engine. It's not uncommon to see a 40 year old K&B 61 still running like new.

If made by hand the ABC engines would be more expensive than ringed engines dur to the required precision, but CNC machinery has brought the price below the ringed engines. ABC uses an Alunimum piston in a Brass Chrome plated sleeve. The sleeve bore is tapered a small amount, being smaller at the top. At normal running temperatures the top is hotter than the bottom, if the taper is right at the running temperature the bore is straight when the engine is warm. While an ABC engine can be ringed, generally "ABC" refers to a lapped fit piston. The lapped piston ABC design gives good engine life and quick break-in. Probably the most common model engine type currently on the market.

AAC is a variant on ABC, substituting aluminum for the brass sleeve. Same characteristics as ABC.

ABN is a cheap variation on ABC, instead of using a chrome plating it has nickel plating on the sleeve. Thunder Tiger has given excellent service with ABN, and their selling price is low, probably in a large part because of the inexpensive ABN process. OS. the other current user of ABN, has a continuing problem with failure of the plating which effectively ruins the engine due to the excessive price of repair parts. Side note: The OS engines with ringed pistons are still of good quality and long engine life. ABN is cheap to make, and is easily damaged.

The early Norvel/AME engines used a variant on ABN, substituting aluminum for the sleeve, becoming AAN. They no longer build any AAN engines.

Other material and construction methods are still in use, but I think I've pretty well covered what you asked about.

Bill.