I think as per the general consensus, this is obviously something dealt with on a case by case basis.
It can also vary depending on the riding occassion. If I'm commuting, then more often than not I shall aim to get to the front when it's safe for me to do so. If I'm pootling home from the cafe after an 80 miler with the club, then I'll usually hover at the back.
I believe that filtering is assertive riding. It tells the traffic that you're going to take control of the speed away from the junction and you're going to manage how and when they overtake you. It gives you extra vital seconds to get clipped it, get going and get in an assertive position. Adversely, more often than not, when you're in the midst of a queue with bumpers on your rubber there's a greater pressure to manage this, especially when the car in front takes off slower than you would like and you lose momentum or if it takes off like a rocket leaving a gap that the car behind will want to fill.
It also depends on how well you know the junction. I pass through many sets of lights on my commute and I know the sequences of all of them. This means I know in advance of filtering whether I can make it to the front before the traffic is going to want to start moving, or whether it's going to be a risk and I should hang back. On an unfamiliar junction I would probably advise a more cautious approach.
And finally, it also depends on the lie of the land. If the queue from the lights is on an ascent then I will always try to get to the front. Usually here it will be flatter and therefore getting clipped in and away is much easier. Stopping halfway up a hill, especially with panniers and racing pedals risks a potentially slower and more wobbly start that places you in jeopardy.