For a number of years I've used several manufacturers of truss and this is by far the easiest to use and because of that I find it cost effective. The couplers are easy to use and the engineering tolerances make the pieces a nice tight fit. On top of that, the quality is good. It looks professional as well as doing what it says on the tin.
I've bought in to the F34 range and know I can keep adding components as I need them without fear of it going away any time soon.
Thomann also have great customer service, so if you get a delivery that has damaged items, rest assured they will take care of it. I've had a few damaged bits, but it's never a problem.