Some professors are very accomplished, others are younger and maybe not yet so accomplished (although admittedly this does not need to correlate with age of course). I presume everyone wants to work with the accomplished people, and not so many people want to work with the people who have just started their careers.
However: Say I really wanted to get into uni X, because of personal reasons (I can't move to a different city because of my wife etc., so just personal reasons; also I do not aspire an academic career after the PhD, I have other reasons for wanting to complete one), would my chances be increased if I were to target a not so accomplished/famous/senior advisor (all other things being equal)?