I'm very near the end of the game (in the midst of Chapter 7), and out of all the boots I've collected, I find speed is the most useful. Sure there are others but they either bump up ONE resistance (eg boots of the north -50% cold resistance but there are practically no monsters that does a cold attack) or have special abilities that can be used only ONCE per day. The speed boots otoh haste the user permanently (at least until the boots are taken off...)
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"Butt-kicking for goodness!" - Minsc
"Cities always teem with evil and decay. Let's give it a good shake and SEE WHAT FALLS OUT!!" - Minsc