I have a 3 horse angle load Discovery.
I brought it new 5 years ago and have not had an ounce of problems with it. It tows like a dream and has never got a sway up or bounced on the rough roads.
The one I have is called a deluxe, so it comes standard with the following.
It has roller rocker suspension
Greasing points for the suspension.
Double floor, timber and metal
Non slip rubber floor and sidewalls.
Rubber drop on front divider.
Urine deflector at front bay with a drain hole.
Two pop up vents at the front.
Two fluro lights with switches
Tinted sliding windows.
Bars on the windows.
Deep well padded dividers, all stallion dividers.
Rug rack over the rump of the horses.
Swingout Tack cupboard
and of course break away unit.
Also has the checkerplate on the front, guards and sidestep etc
Also came with 5 new tyres and nice rims.
Had a choice of a Rear dust cover or doors (swing or strut lift).
The downfalls:
It has had a few annoying leaks that we had to fix around the front window and vents.
One of the springs on the ramp wasn't fitted properly when we brought it and it didn't work, so had to have it fixed.
The smallest horse bay is at the front, so if you are taking a big horse it will not fit in the front bay.
My 16.1hh Andy and TB fit well in the middle and third bay. The thrid bay is the biggest, which does not make sense to me.
The tack cupboard is a bit heavy and we have had to re-inforce it as the welds broke away from the metal sheet.
What I would do if I needed to update? Easy, buy another one of these, but order it a bit bigger to fit the large horses in the front bay.
If I had a money tree, Rivenlee here I come. Or a New Duel Cab Isuzu Truck with custom tack boxes built on the back and a 5 horse Aluminum Gooseneck with a luxury fitout.

(dreaming of a lotto win).