Besides not being Campy
, there is nothing wrong with 105. As far as 105 and Ultegra go there is very little difference except for weight. To a certain degree the same could be said for Ultegra and D/A.
Honestly, 105 is probably the best bang for buck. Well, for ShimaNO anyways
Disclaimer: I have both 105 and Ultegra on a couple of bikes too.