Eibach are top of the range, as well as H&R springs which are 35mm but they go for over £250.
Tein are a bit pointless as they wont make much of a difference in drop on a Sport model which is already lowered 15mm compared to other models.
Haven't heard of anyone using SPax to be honest
I have Apex 35mm which can be coupled with standard shocks, the ride height is great, handling improved and as comfortable as standard.
Anything over 35mm drop and you will find it near impossible to buy shocks that can be coupled, although a lot of people just throw 50mm springs on standard shocks which is not a good thing to do.