Which pretender design is best...?

If I didn't care about Bless Effects I'd probably say the same. As you can Summon Earthpower up to cast whatever you'd like, or Earth Boots to cast what ritual you'd like.

What I do know however, is that CM's and most S&A mages fatigue quickly even under a Magic 1 enviroment.

Though I tend to script my casters with Quickness, Eagle Eye, Acid Rain and other such spells.

Without easy communion Access you will run into situations where your mages will only get a few casts, and intrinsic reinvigoration can help.

If you have the points and the thought of a Natty appeals to you, I'd definitely go Earth at least 3. If you have some extra, putting an additional Earth on him isn't going to hurt and it will allow your mages to recover from sleeping faster to cast another spell.