Airflo multi tip is my pref, but then I like the windcutter multi with multi colored line to let you know where the belly is at. Slap that on some bright colored gel spun backing and it'll look reel perty.
"Everyday that you wake up and decide not to go fishing...is one less day you'll go fishing." Forrest Maxwell
There is more to it than this but here is the simple answer.
Windcutter -- 54' head
Midspey -- 65' head
A windcutter is a great line to learn on as you can load the rod without tons of line out. I, and a number of others, feel it also is more forgiving of falty mechanics so it tends to allow bad habits to form. Takew that for what you will. The Windcutter does handle super heavy tips better than longer bellied lines and if backcast area is severely limited, it will allow you to cast with a minimal D-loop behind you. The down side is you have to strip and shoot line if you are wanting to fish beyone 70'. In winter conditions, stripping can lead to iced up guides, cold hands and less time in the water fishing.
The midspey still will aloow you to shoot if needed but you are out to around 85' to 90' then (depending on leader) and for most situations, the most you would need to shoot is 10-15'. It will handle all the Rio 15' tips no problem and I believe you are forced to learn better mechanics. FYI the Long Delta is also a 65' head.
And then there is the long bellied lines like the Carron Jetstream, Rio Grandspey and SA XLT. These are not for beginners but boy are they fun.
I fish both lines, as well as an Airflo, but I think the ultimate "first" line is the Windcutter.
Sinktip (who casts a mean line with the midspey) said above that the midspey forces you to learn better mechanics. To me, the corollary of that is "it's harder to cast." Most spey people who fish Rio lines would agree that the Windcutter is the easiest to learn. I rarely find the stripping to be a problem (although I don't find myself in really really cold weather that much).
For that rod, which I have never cast so I will defer to others on that, I would bet a Windcutter 8-9-10 would line it great.
Joe, the previous messages hint at the problem facing you. Spey rods are like racing cars, which need well-matched tires (not just something that fits that car's rims) in order to perform.
Let me direct you to the wonderfully informative Fly Fishing Forum (www.flyfishingforum.com). Go down to "Spey Clave," one of its major categories. As it happens, at this time there's a thread under General titled "Our AFTMA rating mess," that will give you some idea of the problems involved in finding the right line for your spey rod, or anyone else's. If you check into the site's Archives, you'll see that that's probably the most popular discussion topic.
Try to show up at the spey casting gathering at the Ben Howard boat launch on the Skykomish this Saturday, Aug. 16, starting around 10 a.m. You'll be able to try out various lines for your rod while you get free casting instruction and meet some of the local spey community.
The low-cost solution, as a way to get you going for the first season or two, would be this: buy a standard DT7F or DT8F; cut the taper off one end (about 8' long); add a braided nylon loop (preferably the heavier, 50 lb. size) to the end of the belly and the thick end of the floating tip; buy some Rio 15' sinking tips, or buy a cheapo #6 or 7 sinking line, cut it up for sink tips and add braided or spliced loops. You'll probably want to get a more sophisticated spey line later, after you've tried others' and found one that you like. But this will get you out of the gate without spending several hundred dollars on misfitting lines.
Circlespey is right, the WC is much easier to cast for the beginner.
If I had to send somebody off fishing with little practice time (say less than 20-30 hours) I would say go WC or Airflo Delta. If that person though had twice that much time and even better yet, a knowledgable teacher to work with, I would lean towards suggesting the mid-bellied lines.
One final thought on the WC. It has been described as both a beginners and an experts line. I would agree with this as it is certainly the easiest to learn on but in the hands of a good shooter (something I have never mastered beyond 20' or so), it can cast a mile. Of course then you get into the debate about the ability to control the flyline (i.e. mend) at distance but that is a topic that we don't need to get into here.
Nooksack Mac's suggestions are right on. Do a search at that site and you will find out all you need to knowe about the 7136-4. A lot will depend on which version you have: the old brownie or the newer green or recently changed other brown one. The older rods are much softer than the post-2000 models.
I am sure someone at Ben Howard will have those lines for you to try out. I was hoping the get together would be Sunday as I am booked on Saturday.