depends on how fast you are throwing, and the conditions. I throw really stable to really understable discs, depending on the hole and the wind. i throw a z flick or star wraith into the wind for long straight hyzer fade at the end, but champ valks or other more understable discs with wind behind to do the same thing.
Try the Raging Inferno. It's overstable to begin with, but when you get it beat in enough that you could turn it over if you wanted to, it's gold. In that 'worn in' type of condition it's still really fast, but has tons of glide too. The curved inner lip feels very comfortable when throwing sidearm as well (not one disc from Innova has this feature, not sure about Discraft...). I'm a sidearmer and it's my main driver; when the wind is calm that is.
I have always used a Whippet about 175g as a model for sidearm (or some disc with a similiar profile) - they take a little effort to break in but then fly in a very predictable fashion with an easily controlled turn for both drives and approaches. The beauty of this technique is that it gives you an always ready "anhyzer" in your bag.
If you can throw a Wildcat 350+ I would wonder why you are looking for a new disc? That seems like a good disc to have.
With little to no wind, a star SL will fly straight as an arrow with great glide. With a cross wind or head wind, I'm throwing a champion Starfire. It will hold a line and end with a little fade at the end.
Good tips from Chris and Ray here - the are using discs with which I am not familiar but they obviously understand the physics well. Sidearm is a different animal than backhand and requires a completely different approach on the tee or otherwise.