miniscule temp differences aside between all the different high end compounds:
Arctic Silver is electrically conductive, there are compounds like TX-3 or IC diamond which aren't, and allow you a lot more peace of mind when using it.
One more thing regarding Diamond: If you have to remove it, kind of gently twist off the heatsink and don't try to stake it straight off...I actually pulled my Phenom II out of the socket doing that, with it still firmly stuck to the HSF...Sliding it off worked fine, and it isn't something that would set into a stuck position, it is just so thick it can hold things onto it.