At new prices?
The 6-36 is a no brainer, especially if you want DTII+ turrets on the 5-25 as that pushes them up to nearly the same price as the 6-36. Given the minimal cost difference I'd rather spend my money on the brand new design 6-36 rather than on the 18 year old design 5-25 (that is still pretty damn good, admittedly. I have 6 of the 5-25s that I started buying back in 2010 and they've never let me down, and using them back to back with my Tangent 5-25s never leaves me feeling like I'm missing out. I keep thinking about selling a few off and upgrading and never do, as every time I use them I realize I'd be losing money selling them for not a lot of gains.)
Even though the US market 6-36 has an artificially limited FOV compared to the Euro version, the FOV limited US market 6-36 still has a slightly wider AFOV than the 5-25, and actually has a much larger FOV on the bottom end because the 6-36 doesn't tunnel from 5-7.5x like the 5-25.
Used is another story. A 5-25 at $2200ish used is a good scope for the money provided you find one with a reticle you like, you don't mind tunneling from 5-7.5x, and you don't mind the finer graduations on the DT turrets... and if you don't like it you can sell it for what you paid for it.
