OH good question! I'd have to say at this point, ligustrum. It's ability to be reduced and ramify, as well is it's tough nature, convert well to bonsai. OH but then theres,....j/k.
Tough one Irene.
Favourite deciduous tree, well semi-deciduous depending on your climate is the Chinese Elm. Bonus is you can root prune them at almost any time and they get fantastic branch ramification.
Steve
Bougainvillea. Unfortunately I no longer have any, having lost two due to the cold weather. The first succumbed to a rare and unexpected 28 degree night when I lived in the Bay Area, CA. The second was lost after moving here to the Seattle area, when despite watching the weather forecasts we were hit with an early October freeze. Maybe someday I'll try it again.