I suggest Excadrill, as his Sand Rush Ability makes better use of of Sand. Instead of relying on probability and Hax for that miss with Sand Veil, Sand Rush is guaranteed.to Double Excadrill's speed.
In addition to this, Double the Speed is a better option for offensive methods, as hitting first and hitting hard with access to Swords Dance make it better choice.
Excadrill Steel typing serves an excellent resistance in the Uber tier, as it resistant Dragon, Ghost (Giratina), and the many Ice type used to destroy them.
Garchomp is also a Dragon type, which is a disadvantage as the Uber tier is dominated by powerful Dragon type.