siege arty is nice.

culvs make assaulting even citadels not that painful.

before cannons, I usually use catapults as the accuracy is better than mangonels or trebs.

I've seen v0 mangonels miss with all their shots and it's pretty frustrating.

catapults bounce low enough to hit and do some damage.

besides, by the time you get mangonels, you can get v1 catapults which are better.

cats also are smaller and wrecked less often.

by the time you get trebs in high, cannons aren't far off so why bother?