I have the SA Wet Tip Express, and it's a great line that casts extremely well. I use it a lot for stream and pond/lake fishing of streamers and it does exactly what you need. It's also great for woolly buggers and nymphs, or really pretty much any flies you want to get down quickly in moderately shallow water. The streamer express has intermediate line in the middle so that you can strip the fly in without having it rise towards the surface too much.
So if you're looking for a strictly streamer line, then the Streamer Express would be a good choice. But if you're looking for a better all-around line, then I'd go for the wet tip express.
My passion for catching fish is eclipsed only by the fish's passion not to be caught.