Imo it's hard to beat large hardwood trees. Difficult to work with but big fish will live under them. Not just occasionally visit it like a crappie pile or similar
Agree 100%. As mentioned Bois D 'Arc is my favorite. Extremely dense and relatively easy to sink (unlike Christmas trees, which like to float like a cork)
They are cumbersome and heavy to manage loading and unloading off your vessel, so be very careful, and obviously wear a life jacket and carry some sharp scissors and some sharp knives just incase.
At times, I've had to saw them into sections to sink on top of each other.
Very dense, so easy to see on the fish finder. As stated, they just don't attract fish, they become a home.
They are best the first three years, then I would refresh them with new brush.