Performance is a tricky, multi-dimensional thing, so there are many benchmarks that try to map to different workloads. For example, specint is often used for exactly your "single threaded task" benchmark, but if what you work on is numerical computing, you mostly don't care (you want specfp at the least and even that is bad).
Some people seem to really like Coremark these days. Others like specintrate. What kind of application do you care about? I'd guess plenty of folks here can provide a better estimate with that info.
At this point Intel literally only makes sense if you have one of those single threaded work loads where it still excels and you absolutely must have the fastest single thread performance.
I don't work with Rails anymore but the last Rails app(single threaded, Unicorn) I worked with raw CPU compute was not the bottleneck usually as with most CRUD apps time was mostly spent in I/O. This effect was so pronounced that I had set up most scaling groups on M or R instances as the memory used by the gems was the bottleneck on the number of Rails processes I could spawn in the box without exhausting resources. However I do remember even if CPU was not the bottleneck, moving to a processor with a better single thread performance did improve the median response time at the cost of making the same request throughput costlier.
Compared to the second-generation Epyc processors that Google is using, the first generation has lower clock speeds, can execute fewer instructions per clock (particularly in terms of floating-point operations), has substantially less cache, and has a more complicated memory topology that can negatively impact the performance of workloads that aren't NUMA-aware.
In short, your experience with AMD in AWS isn't relevant to Google's offerings.