I usually prefer fullscreen DVDs over 2.35 :1 widescreen.
But I usually prefer 1.85 : 1 widescreen (16x9) over fullscreen (except maybe for comedies).
The aspect ratio for fullscreen is 1.33 : 1, and 2.35:1 requires giant black bars at the top and bottom of the screen. That can be annoying. Everything is shrunk down, and a lot of space is wasted.
The aspect ratios 1.78 : 1 and 1.85 : 1 (roughly 16x9) require smaller bars — which I can tolerate more easily.
Some companies do the smart thing and put both the Fullscreen and the Widescreen version on the same disc. (Sometimes the disc is double-sided.)