Well Grasshopper, you ask a philosophical question that only you can answer! Do you mean that you want to buy yourself a new (newly manufactured, like the Classic series) revolver, or a "new to you" (used) revolver? As far as Model 10s and 19s, there are many, many choices for both brand new and used. You must also ask yourself what is the intended purpose for the revolver: range, CCW, walking in the woods? That would help with determining barrel length and finish (blued, nickel, or SS). I like rear target sights on my revolvers so I tend to shy away from M&Ps and Model 10s. But to each their own. Most of my modest collection is comprised of N-frames, but I do own some M&Ps and Model 19s and they're fine revolvers.
Since it's for your birthday (congratulations BTW!), how about splurging on one of these Model 327 WR (Jerry Miculek) in 9mm? Or what about the PC Model 19 Carry Comp! I think those are really cool, and I think that Performance Center revolvers are worth the additional cost for the upgrades. Good luck with your decision!