I like converting the Harriman xAKs to AKEs, and usually convert a few Hog Islands as well for good measure. The more I play, the more I like AKEs, AEs, ADs, ASs, etc. Since reading "Beans, Bullets and Black Oil" I've had a lot of respect for auxiliaries.
A lot of the Brit xAKs convert to xAPs. They are usually better as xAKs in the beginning for moving supply and fuel (at 50% efficiency), but at some point most of them become more useful as troop carriers.
Also, keep an eye out for anything that can convert to an AKV. I don't recall what classes they are, but they are definitely worth protecting.
I never read my opponents AARs, but aux ships are usually under used. I like and use them all heavily.
The ships are force multipliers. Someone who does not use them will have to send his ships to major ports to rearm and repair. That wastes fuel and time, both of which could be used for other things besides clogging up the major ports repair facilities with lots of minor damage to repair.
Even the AGs are very useful in that they can repair damage, including major damage, to very small ships while still being cargo haulers. Useful for convoys, plus they can be loaded instantly in San Francisco.
Seek peace but keep your gun handy.
I'm not a complete idiot, some parts are missing!
“Illegitemus non carborundum est (“Don’t let the bastards grind you down”).”
― Julia Child