I use a variety of thicknesses and vary it for given recipes based on traditional styles.
I use thicker mashes closer to 1 qt/lb for English and UK styles and more traditional 1.25 to 1.75 qt/lb (for highly attenuative styles) for most other styles. From what I have seen documented, only mashes outside of the usual 1.25-1.75 qt/lb thicknesses will give you anything but very nearly equivalent results.
That said, I also try to adjust based on mash schedule. If you are going to do a multi-step infusion mash, you will want to start thick and add judiciously as to not end up exceedingly thin. Likewise, if you are doing decoctions (usually attenuative german styles that you are trying to keep a lot of malt character), you can start out right in range and stay there through mash-out. Also, I fly sparge, so I do value a thinner mash to a higher degree than batch spargers might.
Obviously, YMMV, but I don't think enough evidence exists to give anyone enough conviction to tell you there's a right or wrong answer here.