It's mostly up to you really. I don't play AST much myself but I find myself not caring much either way when I'm WHM. HoTs, when stacked, are quite good at keeping a team up but shields can save people from dying outright. If I had to pick, personally, I would use NoctSect with a WHM since having Shields+HoTs is always better than just having HoTs. Though it really doesn't make that much of a difference outside some of the more difficult fights.