> HAL will faster than direct access.
No. Who told you that?
HAL functions themselves are accessing the memory mapped registers directly, there is no other way, but they check a few things in the handle structures before each access. This makes them a lot slower than a simple register access. See the result here.
> HAL will offer more easy to remember the function names
HAL function names might be easy to remember, but they are poorly documented. HAL documentation is most of the time a single sentence for each function or parameter, not really explaining what it is exactly doing.
On the other hand, registers and bitfields are extensively documented in the reference manual, with timing diagrams and step-by-step examples on how to use them.
> HAL will make the code more portable.
In some special cases. Otherwise HAL is not even always compatible with itself, the behaviour of functions are sometimes changed between releases. The register interface is guaranteed to remain stable throughout the lifecycle of the product, i.e. at least 10 years. There are no guarantees that HAL will be available next week, ST can abandon it any time like they did with the SPL library.
If you want to continue, you can find a few more "advantages" of using HAL here.
