One thing the Russians are very proud of is their automatic loader, which enables them to use a three man crew. The Arjun (like all western tanks) has no autoloader, and uses a 4 man crew.
It turns out that if you are doing extended operations, with crews pulling their own security, it is much better to have a 4th man to split the guard shifts. Also, the autoloaders can jam.
In the first gulf war, you may have noticed all the burnt up Iraqi tanks had their turrets blown off. This is because the autoloader uses ammunition stored in a vertical position, around the turret. In western tanks, with manual loading, the ammunition is stored horizontal, usually behind a blast door, with weakened blowout panels above, to direct explosions out.
For this reason alone, I would put my money on the Arjun. The Russians’ stubborn use of the autoloader has always been a problem for their tanks.
As far as I understand like any weapon system autoloader has its own disadvantages and advantages.
http://en.wikipedia.org/wiki/Autoloader