One of the Jap 4x4 lads has an Oztent, great thing but carries it in a roof box on top of his Patrol and has to have a hand to chuck it up there. I's floor footprint is way more than any roof tent can offer.
On the subject of roof tents I've had a few variations:-
Maggiolina, pretty quick to erect and fairly quick to put down, limited for size and a bit old but quality made. ok just for sleeping. Have it on the 80 for laning.
Ikamper2, Great thing, plenty of floor space, pretty well made. Doddle to put up, about 3 mins to put down, my favourite. Good space with the awning.
Pathfinder, Went up and down at the touch of a button, bit short on room like the Maggi but we had no issues with ours.
EasiAwn, we have this on the Metalian trailer. As it's a fold over it's a bit of a faff packing it away but there is more room than the Maggi and Pathfinder. Maria likes it to sleep in.
Next we're going to try one of the ones which open from one end. A few of the lads have them and think it's the way to go.
These days there is a vast range on offer to choose from.
None of the above have ever leaked in whilst camping in the rain