For what the MagSafe is designed for, the T connector is undoubtedly better. It doesn't really matter which way the cable is going, it's still going to disconnect when someone trips over the cable. In my experience, with the L connector, if someone tripped over the cable in the direction where the plug is connected:
the cable either doesn't disconnect or disconnects when it's too late (after the computer falls onto the floor or the person trips, sometimes both).
I do have to admit that the MagSafe 2 disconnects a bit too easily for my liking- even a little tug and the plug disconnects from the computer. Probably very safe in the event of someone tripping over the cable, but inconvenient when moving the laptop around. The original plastic MagSafe was great imo, it disconnected only when I needed it to disconnect, simple as that. Shame about all the fraying and fire events reported from bricks made based on that design...