Start with PBP because that is the easy path to succeed. But, once you've driven PBP, you will get curious to know how to tweak it. In PC terminology, I would liken it to overclocking your processor. There is nothing to beat a well written ASM code. PBP is close, but, if you look at the listing, you will see places where you can definitely do it better if you know ASM coding.

So, in short, you learn to drive a basic(PBP) car and then set eyes on a Ferrari (ASM).

As for me, I started with ASM and migrated onto PBP. It was tough, but, it is worth knowing ASM because of the things you can do with a mix of PBP and ASM.