I have both in my effects chain. They are totally different distortion pedals. ........... If you can only choose one, I'd go with the MXR. It's a lot more flexible.
I use all three and an Xotic RC booster on a loop with the wah. The OD-1 I have is just magic. Keep going back to it. The MXR+ is pretty nice by itself, especially just; guitar > pedal > tube amp, but the germaniums don't love the buffering in the loops and it tends to drop out and become less responsive when engaged. It does perk up along with the Bosses. This seems to change with various output impedance loads as well.