I already mentioned Stretch CF
Let me elaborate a bit, other great midsize (I think you mean bigger than Sage or Caly, right?) Spydercos that I have are:
Centofante 3
Centofante 4
Chokwe
Gayle Bradley
Endura G10
Manix 2
Pacific & Atlantic Salt
And if you shop around you may still find a Volpe, a Kris or even a big Persian in your budget
The Endura G10 is excellent and sturdy, as was mentioned above
The Centofantes are splendid slicers but it seems to me that you want something more upmarket
The Chokwe is very interesting, a diabolical slicer with surprisingly good ergonomics. And I think pretty rare.
The Gayle Bradley is a workhorse in gentlemen dress. High performance but it will stain!
The Manix 2 is an undestructible workhorse
Pacifc and Atlantic Salts are very interesting but you want something more chic, it seems to me
From the out of production ones listed the big Persian is something quite special. It will eventually be reissued
All in all i think that the Stretch carbon fibre is the best "compromise" (strange word at this quality level): strong enough for most uses, very good and safe ergonomics, a relatively thin blade for good slicing (thinner than Endura for most of the blade, thicker than Centofante) yet still sturdy enough, a high end steel... and you can even eat with it without looking like a mall ninja. Really an unassuming knife that's a high performer and that will grow on you.