I've spent sometime with this particular question and finally..and very happily, opted for Panda Security as my preferred business solution.
The reason I did so was that their "Cloud" offering, (Cloud Office Protection) is just so much more mature than the competitors, ease of use and functionality is exactly what we needed and with the ability to have a Partner console giving us linked visibility of all our clients under one console was just perfect.
Also we have to consider detection rates, this is a potential minefield of a topic, best thing is to test it your self and don't just believe what your sent when enquiring ! I've found Panda has a fatastic detection rate, and with the new online scanning engine built in has even reduced the possibilities further for zero day threats also.
One of the best things though is footprint, compared to the others I've used Panda was non intrusive into the general operation of the PC's being used ensuring performance was never hindered.. and ultimately the user :) and me.