A lot of players have had good success with the simple Aegis Defence Line - it gives good cover and shootyness to static heavy weapon infantry units.
Personally I'm less enthused by the larger fortifications, if only because something as big as a Fortress of Redemption dominates the whole games table - great if you and your opponent _want_ to fight a fortess-related game, but otherwise it's "oh no, he brought his Fortress again"