I don't really care if I'm on top of aggro list or not, though I'm not one of those guards who get locked out (except when other tanks have much better gear than me but then that's got nothing to do with skill or class balance anyway), there's goad and forced engage in those situations where you really lag behind. IMO tanks should never "hold back" but just fight as hard as possible for aggro constantly. In my experience, whenever a tank starts holding back because the aggro gap is big, there's a big chance that you'll see the top dpsers getting aggro because they saw they could keep on pushing more and more.
Of course it's not always easy to have perfectly balanced aggro with tanks that don't even need to use goad/FE to switch. But gear and AA matter so much in this game, what can you do?
Now as for dps yes guards are behind other tanks and yes conqs are monster tanks now (but I don't know if they have more aggro than guard/dt though, not a lot of tanking conqs on Fury and most of them are not too good tbh)