A buddy of mine used to throw the Valkyrie all the time; I tried it a few times, but it was a bit too understable for me. I've also tried out a Wraith but didn't like the feel of the lip; it's a little bit of an overstable disc so if you're getting a nice, flat flight out of it you're doing pretty well and just need to keep throwing. If it's turning too much on you you may want to try something different; I have had some success with the Beast and Eagle from Innova in the past. The Cobra does fly pretty nice and straight, I know a couple guys that play in the league locally that still use them. I use Discraft's Buzz for my mid-range disc and to me it is the best disc ever made; I throw it on anything out to about 280 ft. I have recommended the Buzz to many people and everyone that has actually tried one has not only kept it in their bag, but picked up an extra. These throws are with the standard Backhand throw. If you throw it flat, it stays flat. If you throw it with a slight hyzer, it holds it and you have a nice slightly left curving flight. If you throw it with a slight anhyzer or right tilt, it will actually hold it and fly slightly turning right. It is the most easily to control, beautiful flying mid-range I've ever thrown.
But yeah, if you've found the putter you like, but several of them and just go to the course or set up some sort of basket the right height at home and just putt from everywhere.