Running anything faster than 2.5G on copper is expensive (Cat6a and hardware), often problematic (heat issues) and bad value (just use fiber or something)

10G with fiber is cheap, including hardware, if you know where to buy. Need more throughput for 1-2 things? Use a LAG.

25G also would recommend if you need more throughput, and the hardware isn’t that expensive either.

40G/100G, don’t. The 4x10G/25G lane setup means you either pay for expensive MPO fiber or end up dumping a bunch on modules. NICs for 100G are a pain in the ass.