I like to use one brand so I can fill bobbins and know what's in them later (they aren't labeled). I like 50 wt or higher because a lot fits on the bobbin and it doesn't have a lot of bulk in the seam.
Talking to other quilters and my own experience, some machines work better with one kind than with another.
Different kinds of peacing/applique/embroidery/quilting and the design of them are done/look better with one type thread or another.
So my answer is: just depends. I like the idea of getting a med grey/tan in several different brands/wts/fiber content and test them out for yourself. Find what works best for you.