I know who the Gurkhas are and they have a very good reputation, I never have understood the tiny Sikh cult at FR though.
Like I said, my ultimate military units would come from the Western ranks.
Their reputation for fierce fighting first came against the Mughal empire. One cool part is that they not only fought for their own religious freedom, but that of other religions under the Muslims. The modern reputation was earned at the Battle of Saragarhi, where 21 Sikhs in the service of British India held off 10,000-14,000 Muslims at a small signaling post between two forts. Eventually the Muslims overran the post, killing all 21. Muslim dead were estimated between 180 (what the Muslims admit) and 450, with many more wounded, almost all through hand-to-hand combat. It was a modern Thermopylae.
Their bravery stalled the Muslims long enough for the British to get reinforcements to the next target, one of the forts, in time before it could be taken.