Which CPU has better Linux Support - Ryzen 2600 or I5 8400?
 

I want to buy new CPU for following use case -

1. running several virtual machines
2. running web servers/databases
3. programming
4. And it should support any linux distro.

Please let me know which CPU is best suited, Ryzen 2600 or i5 8400?

I don't think Coffee Lake has HT or as large a cache, both of which are nice for running VMs.

Lately I've been looking at NVMe for disk performance which seems to have a bigger effect than CPU choice.

VM support needs to be looked at on the CPU specs at AMD or Intel. Some of their models are made for servers and the servers tend to be best for VM technologies. The choice of board is crucial here too.

Many linux users have a preference for AMD but my opinion is that Intel will be more supported as they have provided code to Linux for decades.

Almost every modern amd64 processor is supported in mainstream linux distro's.

Look to benchmark sites for clues to each of your choices. Look at the metrics they post for each test. Your loads may or may not match those but it's a clue.