The 5 tine all-purpose plow is a "chisel plow". Indeed, you could get better results in your situation using a box blade with the scarifiers set down to the maximum and the top link shortened. Go one way and then the other to get a checkerboard pattern. Repeat as many times as necessary.
A turn plow is difficult to pull through virgin ground with a light and smaller powered tractor (21.5 HP) even if it is 4WD. Maybe a single 12" bottom plow would do.
The middle buster will tear up the ground depending on the soil composition. It works similar to a turn plow but doesn't turn over the soil. The soil may have to be worked over in several passes to get penetration and mixing that you want. It makes a bit of a mess.
A subsoiler is just that. An implement used to put deep gashes in the soil to about 8" to 12" deep. It does minimal damage to the top layer of soil.
A cultivator is for use on disced, rototilled, or plowed soil when you just want to churn up the soil a bit to kill sprouts. Often it can be set to work row crops between the desired plants (crop).
If you already have a box blade with scarifiers then that would be my recommendation. It will also bring roots to the top for manual pick up and disposal.