Easier maintenance ARCVT100mkII or VTL mb125

I own the VTL MB-185's. Biasing of the output tubes is accomplished via individual trimpots accessible through the top panel once the tube cage is removed, and adjusted using a narrow flathead screwdriver. Each trimpot is associated with its own meter probe receptacle, the other probe being attached to the 'negative' speaker terminal. The only difficulties, if you want to call them that, are that you must own or purchase an appropriate multimeter (selection guidance is given in the manual), and the trimpots themselves tend to be quite touchy, responding somewhat imprecisely to very small turns. I've used easier (Conrad-Johnson), but there should be no problem doing this operation yourself. As far as retubing goes, VTL runs the tubes conservatively and they should last a long time as a consequence. Tube types are not exotic, rare, or overly expensive, though as usual, expect to pay a premium if you choose to retube through the manufacturer instead of buying from a tube retailing specialist.

All of the above notwithstanding, I'm pretty sure the biggest deciding difference between your contenders will be sound, not maintainance. Search the Audiogon archives for more - related questions have been asked before.