Best Utiility player I've personally seen is Shahid Afridi. He is one guy, who wouldn't get into the Pakistan team for most of his career. Except for that short gap between Kaneria's demise and Ajmal's rise, I dont think afridi ever competed for primary spinner role in the team. Those belonged to, in order of Mushtaq Ahmed, Saqqi & Kaneria, in that order and the overlap between the three (especially the first two) means that till 2002 or so, Afridi is not even in contest for the 2nd spinner role in any format.
Purely as a batsman, he does not make the grade either, in either ODI or Test cricket for Pakistani side, in vast majority of his career.
He is one of their best fielders ever and overall, a cracker of a fielder. He isnt overly athletic in the 'diving stop' sense of the word but Lala has tonnes of stamina and can chase ball forever, is a very safe pair of hands and comes with good reflex stops of the non-diving variety. Ie, in positions like cover, point, etc. Lala is not quite ATG category but definitely in the 'well above average/very competent' group.
But take it in whole: Afridi's excellent fielding, his ability to produce a randomly destructive innings against any bowling on any surface from any position, at a rate that only 4-5 other players in the last 20 years can even compete at and a very efficient containing bowling, with the occasional bursts of wickets makes him virtually indispensible for most teams and there is a role for him even in most test sides. For eg, except the West Indies side of the 80s, Pakistan for a brief period in the 90s, the Proteas in the late 90s and Aussie team of the mid 90s to mid 2000s, I can see Afridi justifying his selection in virtually every test side of the last 30 years as well.
He is by far, the greatest of the utility players i've seen.