This is what i do.

100 traps, 99 abatis, 50 rolling logs, 50 defense trebuchet rest towers a little over 18300 (with lvl 10 walls)

and then 200-300k archers with about 200-400k warriors.

you can add like 10 rams and other units as layers.

1 of trap, abatis, log and DT has the same effect thought they will be gone in one attack. i havent been attacked so cant say how well it works but i know layered defence helps.

for instances someone hit my friend

they sent 100k cav
defense: 1 trap, 1 abatis, 1 log, 1 DT rest towers (lvl 9 walls)

about 220k archers-260k, 400k warriors, 4.4k cataphracts 50 cav and a couple of others.

he lost all the cav my friend lost a trap, abatis and DT and the cataphracts and the cav.