While autobias is certainly more convenient, and I do not know if one is better than the other sonically, I have heard manufacturers claim that adjustable bias normally yields longer tube life.
In fact, Rogue's new amplifiers have made the switch from autobias to user adjusted bias. In addition to the tube life, I have read they feel it also has produced better sonics.
If sonics were equal, obviously autobias is preferable. If there is some audible improvement by not implementing the circuit, it would be good to go in that direction, and make bias adjustment an easy task, with easy accessibility to the adjustment (like AtmaSphere, Cary, CJ, Jolida, Quicksilver, but NOT like Jadis).