More than any other Mac, the MacBook benefits less from faster CPUs because of hardware design constraints.
Since there is no cooling fan, the system will manage the CPU so it does not exceed a certain temperature. For processes that require an extended CPU load, that means the system will throttle down the processes. So even if you have an i7 1.4GHz CPU with Turbo Boost to 3.6GHz, it won't run at 3.6GHz for very long.
My four year old MacBook Air (11" 2013) is actually about 10% faster at transcoding video than my i7 MacBook 2017. That's because it can rev up the fan to deal with excess heat.
I bought the BTO version of the MacBook because I wanted 16GB RAM and the 500GB SSD. Make your purchase decision based on RAM and storage, not about the CPU speed.