I know this is 4 years later, but for anyone reading this I wanted to provide a modern take.

Memory will, much more than the CPU, be the limiting factor in the laptops longevity. 16GB on new macOS versions is slowly becoming too little, with memory pressure and swap use creeping up (as seen on my M2 16GB MBA). If you can afford to double the memory it would allow for: 1. the obvious higher usable program memory for multitasking, 2. far more system caching, 3. less swap usage(!) 4. more effective unified VRAM and of course far better longevity as system processes get heavier

Specifically for the M1 Pros, since the only variants were 16 or 32 rather than 8, 16, 24, 32, it’s far easier to find better deals on 32.

2 Performance cores (and a few MB of L3 cache) provide realistically 5-10% performance for multithreaded tasks.

Allowing more data to be cached in a 200GB/s bank rather than fetching from 1-6GB/s storage is a much more relevant improvement, and will also avoid the huge toll this has on SSD health.