You may get as many different answers as there are ULF photographers. Mine is an antique Gandolfi tripod, just as strong and well-made as their cameras. The big camera support plate is a definite advantage with wooden ULF cameras.
If you really mean ULF (i.e. bigger than 8x10"), then there is a real difficulty in finding a worthwhile tripod that you can carry any distance. I personally use 4x5" to 8x10", outside with my 4x5" Crown Graphic I find a Manfrotto 055 tripod is good if used with care, while in the studio a Manfrotto 058 handles just about anything. As the Manfrotto 058 has the "triaut" mechanism (all 3 legs controlled by a ring under the tripod head), I do not like to use it in dirty conditions (it copes OK but it needs a wash down and spray with WD40 afterwards), so I keep an old De Vere tripod as a standby for a heavy support for outdoors.
The answer is completely dependent upon the camera that will grace the tripod. If you shoot an older Korona you could easily use a Ries J100 and not have to many mobility issues. My 34# Wisner 12x20/8x20/11x14 Tech Field requires a Ries A100 that tips the scale at #13 just for the tripod. That is nearly a #50 camera/tripod combination. Aside from regular visits to the gym to lift weights you learn rather quickly to be highly selective where you drop legs. Gitzo produces a carbon fibre tripod that is interesting and very light weight.