LM317 with a load of less than 1.5A
Downsides:


Ancient technology
High drop out (about 1.75V at ambient temp and 300mA) so you need an input voltage at least that much higher than the output voltage.





Relatively high current draw even when not loaded


Advantages:


Ancient technology - there's tips and tricks and schematic examples for it all over the web.
Ancient technology - mounting a TO220 or TO3 part is easy, even for the mechanically challenged.
Can handle high currents and large difference between input and output (if you use a large enough heat sink)