You may be searching for the ideal practice — the one with the right text, the right length, the right depth. Set that search down for a moment.
The question is not which practice is best in the abstract. The question is which one you will still be doing in three months when the novelty is gone and the resistance has arrived.
A practice you keep is worth more than the one you admire.
Repeatable beats remarkable
A small thing you repeat reshapes you in ways a large thing you abandon never can. This is unglamorous counsel. It is also the only counsel that has ever worked.
Choose something modest enough that doing it is almost embarrassingly easy on a normal day — because the normal day is most days, and the practice has to survive most days. The tradition's long love of consistency in learning is not a love of smallness for its own sake. It is a clear-eyed bet on what actually accumulates.
Make the entry low. Let the depth come on its own time.
Let it earn its growth
Once the small thing is genuinely repeatable — once it has become a part of the day you no longer negotiate with — it will ask to grow. Let it. But let it earn that, by first proving it can survive at its current size.
What the practice should be, and when it is wise to let it expand, are matters for a teacher who knows you and can tell the difference between healthy growth and restless ambition. Your job for now is humbler and harder: find the small thing, and keep it.