MESA Card Recommendation

For a simple 3 axis system, I would suggest a 5I25/6I25 (PCI/PCIE) and whatever breakout board you are currently using
If you want an Ethernet connected system I would suggest a 7I92H+ your breakout

Maximum 5I25/6I25 steprate is about 4 MHz, maximum 7I92 steprate is about 10 MHz

Thanks! Yes, this is the other on what I looked. 4MHz looks more than enough.
When do I need a doughter card?

Or not!? For 3000rpm I need 12MHz with the 1000ppr encoder.

3000 RPM with a 1000 PPR encoder (4000 quadrature counts/rev) is a 200 KHz count rate

(50 RPS * 4000)

Ohh, yes, I calculated in minutes. Anyway, I can use the ethernet type with a laptop as well.

You should be aware that laptops in general do not make good LinuxCNC hosts

This is because they very often have power management hardware/software that cannot be disabled
and that causes large latencies. Some Laptops may be OK or at least OK until you change the backlight brightness
or change from line to battery power etc etc