Yeah, I've seen an equal amount of both tab-up and tab-down, and I too get frustrated by it sometimes.

Of course, the worst is when you're reaching around behind a tower-case PC where the ATX motherboard is vertical, and you're trying to guess left or right.

And then there's the hubs with two rows of jacks: Those are most logical when arranged with the tabs facing outward (one up one down) so that you don't have to reach between rows of plugged in cables to reach the tabs.

I agree that having the LED indicators in the "most visible" position is the most logical (i.e., tab up for ports with built in LEDs), but I have a personal preference for wanting things to be tab-down:

Dust.

Sometimes a given ethernet port will spend large portions of its lifespan with nothing plugged into it. During that time, if it's a tab-up port, dust can settle on the connectors, making them less likely to give a good connection when the port finally gets used. If the port is aligned tab-down, the dust settles only on the tab click-in plastic bit, not on the connectors themselves.