If you have limited room behind you when you cast I'd look at a Sandi line or a Skagit. After you cast you'll have to retrieve some line. A skagit line is great for handling sinking lines and sinking or heavy flies. Also, I believe it is the easiest line to learn to cast. Depending on the length of your rod, you might also need a skagit cheater. A Scandi line is quiet on the water, but IMHO, setting up an anchor with a Scandi can be difficult. These lines work best with polyleaders.
If you have more room behind you. and don't want to retrieve too much line, I'd look at a Windcutter, but I'd probably go with a lighter one for your spey rod. (Go to the recommendation chart at products and supplies
Also, I believe the head or belly of your line shouldn't be longer than about 4X the length of your rod.