We use regular, actually probably the worst - silicone based - lube. It works for us and doesn't "wear off" halfway through. We don't use lube sometimes though, just depends on how much I need.
We used pre-seed off and on when we conceived DS. I don't think we were using it when we ACTUALLY conceived DS, but we used it that cycle. I used the applicator and put it up in there first, I vastly preferred that to trying to actually use it like a lube. Too watery.