FWIW, our experience was different: I benchmarked our Node apps on C6g, C5n, and M5zn and found Graviton to be 10-25% slower in our CPU-bound NodeJS code than the same code on x86. Graviton give you better relative performance per dollar, but for absolute single-thread performance M5zn is still the best choice for us.
Arguably, if you're using AWS, you've already compromised to a point where scaling horizontally is your path forward.
You've likely given up much more than 10-25% by using AWS in the first place (note to the false dichotomist: this doesn't mean owning your own servers). And paid a premium for the privilege.
If you're CPU-bound, get a E-2288G (or whatever the commodity chip that maximized price/$$ is right now) and set mitigations=off.
I think Google Cloud requires less domain-specific-knowledge, which is a big plus. And, as a consequence, you're less likely to end up with an expensive and complicated mess.
But if price or performance or user privacy is a concern, none.
I'm a big believe in dedicated hosting. There's tens of thousands of options. Not affiliated with any, but in the past/present what I have/am using and would recommend: webnx.com, reliablesite.net, hivelocity.com, hetzner.com, ovh.com (and their other brands), leaseweb.com we're currently considering phoenixnap.com for a warm-standby DR site (but no experience with them yet). Also, Softlayer pre-IBM acquisition, but that's just sour grapes.
Yes, starting with Linux 5.2, a bunch of mitigations can be disabled with that 1 boot option. But that's just a small part of where the performance gain comes from. The real win is just recent, dedicated and non-virtualized hardware.
