Is it better to buy Catalyst 9300 with 8 10G port network module or Cat 3850 12 port fiber switch ( stack)
We are looking for upstream switch with L3 and SDA capabilities.
Definitely 9300 as it's newer architecture.
Check this comparison:
When it comes to routing, neither can hold full BGP table so you can't use them for that purpose.
But, for example, 9300 has a limit of 32,000 IPv4 routes, while 3850 has a limit of 24,000, and so on.
Well, it's really up to your needs. The question is what is more important to you. Four additional fiber ports on 3850 or additional features of 9300? In any case, you can upgrade 9300 with additional modules to support the growth rate in future, but you can't 'pimp' your 3850 any further.
I hope this answers your question.
CAt 9300 is the better option and cisco more promoting Cat 9300 rather Cat 3800.
Both run same IOS XE, But you have new chip set in Cat 9300 and more addong features like SD-Access, DNAC and more in th e future point of view.