I have an early model of the Oasis and I can't let myself sell it off. I have several "High end" regs, but that old thing just breathes like a champ still.
hudson above is right. Get the features that you'll need, not that are gimmicky. And thinking down the line won't hurt either. My upper end regs are just because I needed something to put on the manifold in the correct positioning.
Other than that, I vote for the "KISS" method of buying. More "features" often means more opportunity to fail or need tuning/repair. I own several Mk2+ regs also. When I sold MK2+ Regs in the shop I used to compare them to a US Army jeep. Not high tech, not the prettiest, but they take a beating and will keep going forever.
And by the way, only the owner made more if we sold high end stuff in my shop. I always tried to match what the person wanted. That included working out a "rebuilt" deal occasionally for some people. That also included titanium regs for those that thought that max $$$ meant max utility. (Hey - if it makes them happy, who am I to argue?).
I know not everyone worked like me, but it torques me when people on here talk like everyone in a LDS is out for $$ alone. Use common sense like everyone else. If they're trying to "up-size" you like a used car salesman, walk away. A good LDS knows it is about the long term, not that day's sale.
Enjoy whichever reg you choose.