From a purely pre-flop EV perspective:

ATs: ranges positionally from +0.19 (from the SB) to +0.46 (from the button)
ATo: is actually NEGATIVE EV until you get to MP, ranging from -0.08 (from the SB) to a max of +0.06 from the button.

Meanwhile,
KQs: is +EV across the board, and is pretty much better than +0.35 except from the BB where it's only a +0.17.
KQo: also +EV all the way, averaging about +0.10.

Heads up, ATs is a 58-42 favorite against KQs (of a different suit), ATo is 56-44 against KQs.

They're pretty much coin flips, and I see KQ as the better hand because it's easier to let go. If an ace falls, you know you're in trouble. With ATs, a king falls, and you'll usually keep going in the hand. You waste more bets with AT than KQ. Remember, the best hand in poker is the one you throw away when beat.