I have owned the original CETME, original AR-10, HK-91, HK-93, PTR-91, and Armalite AR-10T, starting back in 1970s.

My HK-91s shot very well. I happen to like the drum sight, and with a tree for a rest, offhand can hit a milk jug at 400 meters.
The HK and JLD are very simple, rugged rifles. Their are few parts, and you don't need to completely take them apart, just field strip them. Like the USP handguns, they just keep working.

The AR-10T, like the AR-15, has way too many small parts.
But you can do most maintenance with just field stripping.
My AR-10T is a very heavy rifle, with its 24-inch Walter Lothar bull barrel. It groups into one tiny cloverleaf.

The HKs are just normal heavy.
All battle rifles have to have some weight to them. Hoist a Garand or M-14 or FAL.

My AR-10T is like new, and for sale.