Considering both for a single speed rigid, that’ll be thrashed in the mountains. Middleburn would be external bearings. White Industries would be square taper BB.
Rounding off numerous LX cranks in my youth has put me off square taper. On the other hand, external bearings have their reliability issues. Will be fairly dry most of the year.
Thoughts or experiences of either please.

Middleburn, but RS7 square taper on both my bikes. Have been using them for over 10 years with no problems. One is a Duo, the other an Uno. (second set with Uno only bought last year).
Guy I ride with has the new ones with an external bb on his singlespeed and seems happy.

I’m also a square taper Uno user here and can report no major problems. On purely aesthetic note do you intend to look at the silver or black finish on the WI? I personally find the black version a bit boring as you have this big flat surface area on the crank arms.

I’ve got Middleburn X-Type (HTII) set up with double and bash on my bouncer and love them. Certainly had no issues with external BB in general. As soon as I have the funds I’ll be getting an (X-Type) Uno to go 1×10 on the HT, might be a while though!

I have used both in the past. Both are good answers to your question, if somebody put a gun to your head which would you say?

I have both, ENO’s are on the bike, UNO’s are on the bench

WI ENOs you can reverse the ring when it get worn so get double the life, which cant do with UNOs

Been riding an uno for years no issues at all