[Halancar]

Those middle pretenders can all make good SC if you equip them (plenty of hp, the equipment can take care of the rest). They can usually give a decent bless (if their starting path match what you are looking for). And even without the bless, their good starting path mean you can easily boost them to where they'll cast the later game powerful spells. Particularly if you are planning to cast powerful battlefield spells, they won't die to a lucky arrow or an assassin.

I think they are a sort of compromise : you can get a better bless (usually) with a cheaper chassis, and there are better SC chassis and artillery chassis, but if you want a bless AND a SC, look for a titan.