If you want the best performance from your mountainbike, you should seriously consider Shimano XTR bike components, because no other Shimano component group offers that much performance at such a low overall weight.
When the Shimano XTR group was introduced in 1992, it was an extension to Shimanos existing high end strategy. Until that time only the Shimano Deore LX, Deore DX and the Shimano Deore XT group were around. While the first XTR group boasted a 20% weight saving over the LX components at the same strength, later groups were advertised with increased durability and lower weight.
Until today Shimano XTR bike parts have kept their fame to be the best mountainbike component group. This results in an expensive price level. The group consists of a crankset, hydraulic disc brakes, shift/brake levers, rear derailleur, front derailleur, chain, cassette, hubs, pedals and wheels. The function of every part is synchronised to each counterpart resulting in a perfect performance and an overall weight of only about 1750 g (without wheels or pedals).
Contrary to the road groups, where Campagnolo competes with it's Super Record groups, Shimano has almost monopoly in the MTB market. Only the american component manufacturer SRAM offers a similar group called XX.
Shimano XTR components are available in two version: the „Race“ (2x10) and the „Trail“ (3x10) versions.