I got to use both pedals. And it really depends on the type of distortion you are looking for. The MXR Distortion+ does one type of sound only, like an overdrive/slight break-up or distortion. It does this sound very well though. Think the Police song Roxanne. It kinda sounds like that, very mild.
The DS1 is more versatile. It can get the Police sound and other more distorted sounds. Think alternative rock, nirvana, etc. The bunyok mod would really be great to tone down the harshness of the distortion.
Based on your tastes, buckley, tool, page. I think you need a good overdrive/gainy distortion pedal. Not a DS1 or MXR. Maybe an SD1 or a RAT. But if you have to choose between the two. I think a modded DS1 is the way to go. It won't get you exactly the sound you need but it will be close enough and would be more flexible.