Interesting subject. I, too, often get the itch to try something new when it comes to guns. I don't know why it's this way, but it is. A few years ago, I resolved, for both practical and financial reasons, to not have more guns that my modest gun cabinet will accommodate. Since then, I have swapped and traded a lot; when I want something new, something old must go on the auction block. Yes, parting with some guns can be tough, and sometimes regret sets in later, but this happens a lot less often that one might think. I think this is because, on the whole, my gun collection gets better with each successive trade. Rather than increasing my numbers, I am able to invest a little more in the same number of guns at each step. So, whereas I used to have only one or two really nice firearms and many more middle-of-the-road specimens, a little diligent and thoughtful trading has now yielded a collection that is mostly of the nice or very nice variety. To boot, I've been able to try lots of guns that I otherwise would not have had the pleasure of owning, even for a little while. This has gone a long way toward refining my tastes and helping me appreciate guns I truly enjoy keeping and shooting.
All that said, I would not decide what rifle to sell until you decide what new rifle you want to buy. Selling any of your three rifles would produce enough cash to buy something quite nice. Rather than looking to fill a hole in your line-up, look for something you'd enjoy more than the rifles you currently own. Maybe you'd like a semiauto (AR15s are fun), or perhaps a handgun or shotgun would be to your liking (assuming you don't have one already).