The LM20154MH/NOPB: The 1 MHz switching frequency lets you use a smaller inductor and fewer output capacitors than a lower-frequency part, but the layout must keep the high-current switch node short and the feedback trace away from noisy copper.
The synchronous rectifier (internal low-side FET) keeps efficiency above 90% across most of the load range, which matters when the 4 A output is running near full current and the board has limited airflow.
The part is ROHS3 compliant, and the tube packaging is standard for prototype and low-to-medium volume builds; for reel quantities, check the alternate order code suffix.