Neither system is useful to me in a second focal plane scope unless I'm at max magnification anyway, so having a first focal plane reticle is more helpful to me than debating which angular measurement system is better, unless I'm assured my targets are going to be at distances appropriate for using max magnification. But once I have a data card built for a load, then only elevation clicks matter and a second focal plane reticle is no handicap on elevation adjustments.
I still prefer a first focal plane MRAD reticle for wind holds, rangefinding, and target/object sizing at known distances, but it's not a deal breaker for me. The only things I insist on are a scope that tracks through adjustments, and I must be able to feel the clicks as I make those adjustments. I've used $80 scopes that did both of those things well, and $800 scopes that couldn't do either.
What I won't ever touch again so long as I live, though, are mixed systems: MRAD reticles and 1/4 MOA-per-click turrets on the same scope, "BDC" reticles with 0.1 MRAD clicks, and so on. They don't matter once I have the data cards made up in clicks of elevation (ignoring whatever values are etched on the turrets), but I have gotten myself confused on the range a few times using BDC or inaccurately scribed MRAD-based reticles with MOA turrets or dials.