What Mating Nuc do you use and why?

[Plenty of honey]

Only my first year with a better set up and equipment. I use the Mini-Plus system.
6 frames, half the size of a Dadant super frame. ( so four frames are the same size of the Dadant standard brood frames in surface area.
These are polystyrene. You buy in kit, paint them then put them together. the paint glues them all nicely.
We make the base and also a decent roof.
The best thing about this system is its so adaptable. If you hives get too full, you can simply add another level ( 6 frames) when your ready you break it down again and give it another virgin queen.
Overwintering queens can be harvested, then sections put together to make a single hive, then broken down again when your first spring virigins are ready.
Like most other types i agree, but this just seems more flexible.

 

[Finman]

.
I use 3-frame langstrots in mating. Then there is no hurry to move mated queens.

During first 10 days it is enough when nuc has one frame of bees.

If nuc is filled with honey, you just take honey frames off and give new empty combs. That happes often during flow.