I've had the thule, Kuat, swagman xtc and semi 2.0, NSR4, the Softride Hang5 and the Saris Cycle On Pro. Also run a number of roof mounted racks. Some are a bit outdated.. but maybe the info will be helpful anyways.
Here's a quick run down of my opinion.. (my own opinion… others may differ)
Thule t2
Pros
-thule quality
-expandable
-usable for light off road with light bikes
Cons
-Cost
-Overall size sits to high when folded and to far out when down
-sits low on hitch and hits ground easily
Kuat
-Fit and finish are incredibly nice
-alum construction
-attractive design when folded down
-additional option available
-good approach angle - because the nature of the pivot and the compact design the rack did very well going through wash out
-expandable
Cons
-very large when folded up, blocks plate
-because of its nice finish it would be a shame scratch it in the gravel…
-still not cheap
Swagman XTC
Pros
-costs the same as a cheeseburger
-great for the "I use my bike once a year for the sea wall" kind of person
Cons
-a cheese burger would hold the bikes better… don't even bother
Swagman Semi 2.0 (my personal favorite of the bunch for 2 bikes)
Pros
-Price
-Size When folded up the swagman is very small and does not interfere with many vehicles license plates.
-when folded down the rack is also very tight and compact
-good approach angle - because the nature of the pivot and the compact design the rack did very well going through wash out
-usable for light off road w/ lighter bikes
-Swagman as a company - my XTC actually bent (badly) being used in gravel. Swagman sent me the Semi 2.0 free as warranty. Great service.
Cons
-fit and finish leaves a bit to be desired, after about 4 months rust began to form a few spots though it was nothing serious
-weight though its really not all that heavy the rack is still made of steel instead of alum. this is noticeable if you are a smaller stature person
-non expandable (the 4.0 solves this)
NSR4 (current rack)
Pros
-fast and efficient
-strong and usable on rough roads (it sees a lot of horrible roads loaded with 4 DH bikes)
-price, relatively speaking its a decent price for what you get.. yet still expensive for what it really is.
-Local company
Cons
-Some smaller persons may have issues loading their bikes on
-can look a bit odd on cars IMHO
-won't hold all types of bikes (though the NSR4 can hold 2 road bikes if you hang them by the bars)
Softride Hang5
Pros
-Holds 5 bikes
-very cool parallelogram system to lower and raise rack
-usable for rougher off road
Cons
-weighs more than the vehicles its attached to
-sits MUCH to far out the back of the vehicle
-lower wheel brace sits very low, cannot be moved and is right in the "hit and run" zone
-fit and finish are lacking (large amount of casting flashing)
-This thing is massive… it requires its own storage shed when not on the van.. and 2 people to move it
Saris Cycle OnPro (I have one I'll sell cheap with the extension)
Pros
-tire style hold down
-expandable to 4 bikes
Cons
-sits to low, not usable off road, drops bikes on rough terrain
-competes with the softride for the heavy weight title
-some cheap components