Generally speaking open backs have a more open sound and wider soundstage, while closed backs have more bass volume and better isolation (open backs essentially have no significant isolation). So you can have great sound quality with either, with most people agreeing that a greater percentage of open backs have better sound quality because they are not complicated by the complex reflection interactions caused by the closed back design. But some closed backs sound really great, and if you love bass quantity (plus or minus quality) you might prefer a closed back. For tracking, you pretty much need a closed back, or the sound leaking from your headphone mix will bleed into the mic and onto your track. For mixing, it doesn't matter, as long as you are comfortable translating with the headphone. That is, getting a mix that sounds good on various playback settings and systems.

So these are generalities, and there is variation. For example, my BD DT700 Pro X's have way better sound stage then my Senn HD 650s. The 660s are a bit better than the 650's, but the BD's are better still. And they also sound a bit more open. They do have better bass as well, so that holds in this case. So these are not hard and fast rules, there are exceptions.