I generally look at highest damage, healing and objectives points and try to come up with a reasonable vote based on those, unless I've seen something in particular that stood out.
I was frustrated once in that there were two healers that did a hell of a job keeping me a live, but I could only vote for one of them
I think it may be nice if the objectives points stat was made a little more transparent.
Perhaps if we could tell from objective points (or a new column) who had either scored or assisted with a score (e.g. carried ball in last x yards of arena without enemy / no posession) in Huttball, who capped in CW / NC or who planted / defused in VS. This would make it easier to spot objectives-based players after the fact, at least. I know there's more to these things than "Ug! Me score, me most useful", but knowing these things could be useful in MVP decisions.