This is a really great topic and I'm sure there are more than one good answer to your question.
On general principle you'd want the location of the anchor cleat to minimize the force applied towards overturning your kayak, right? In an emergency you want to be able to ditch the anchor in a hurry, and in the meantime you want to avoid having any unexpected pull on the anchor flip the boat.
So, for example, the worst place for your anchor cleat would be the back rail of your kayak seat. It's both high, with a long lever arm to tip the boat, and also hard to reach in a hurry. Somewhere down low, and within easy arm's reach would be better.
If you put the cleat on the centerline in front of your seat, it would be much better. Easier to reach and less leverage to tip the boat. But the action of the anchor line, leading over the rail and down to the anchor would still try to tip your kayak over in an emergency.
To minimize the tipping action, you could put the cleat on the side of the kayak, just above the anchor trolley line. That would still be pretty convenient but the pull from the anchor would be almost at water level and shouldn't exert much force towards turning the kayak over at all.
I could be missing something here, but I think your best bet is to put a cam cleat or jam cleat on the side, of your boat. If you're using a sidewinder or Palmetto Kayak quick release with a float a quick snap of the anchor line can free it (and you) and you can come back and retrieve the whole setup at your convenience.http://palmettokayakfishing.blogspot.co ... ystem.html