I think you'd be hard pressed to beat a Shirogorov. They're pricey for sure but not compared to the $2K+ that some are asking and somehow getting.
Also like Sonnydaze mentioned, the Brad Southard Avo is nearly impossible to beat at its price range. I mean, sure you could get a Zero Tolerance chunky heavy thing for 1/2 the price of even that. The Avo is right in the middle, Shiro's knives then split the middle again with, IMO, ridiculous- beyond that. At some point it is gadgety jewelry with the unlikely potential of being a cutting instrument. Clearly that's cool if you're rolling in buckage!
Personally I would and do pay little attention to the trends. Like bearing pivots... (IKBS, ect.). Sure they're neato but where they add a functional lessening of resistance in this particular hinge, they also take away surface area at the most critical fulcrum point. The less surface area at the fulcrum increases leverage which weakens the pivot. Of course this only really applies to "prying" type use, which is to be avoided anyway. I just don't like to close the doors of potential if I can avoid it. The one and only maker that I know of who actually has considered this and implemented it in his knives is Chris Reeve. No knife out there has more under load surface area than the Sebenza 25. As far as a flipper as an opening method there is only one real benefit, IMO. It does "clean up" the blade... no studs or holes to get in the way of cutting and/or gunking up. I suppose it does also offer a "fun factor" which I will admit IS of the utmost importance. That said, the knives I've had or have with the most fun factor are, #1 - the Strider SnG & #2 - the Benchmade 940. Also the almost hydraulic feel of a Sebenza's pivot action is something that simply cannot be bested.
All in all, if you're still hell bent on a flipper knife, my most thoughtful recommendation is the Southard Avo.