Thanks mudgel - it's a hard decision ;-)

I had to bump, just out of respect for number of views!

Hello, how about Sonar and Focusrite 18i8 2nd gen ? Can it record audio on 64 samples and 48kHz with no dropouts and cracks? Thanks.

The Focusrite units can record/playback glitch-free at a 64-sample ASIO buffer size.
Your machine is a big factor in playing back glitch-free.
The load you're trying to run is also a big factor.
 
Both RME and MOTU offer lower round-trip latency than Focusrite.
That may... or may not be important to you.
If you haven't purchased the audio interface, I'd steer you toward to Ultralite AVB over the 18i8.
 

Thank you for your fast reply. I haven't purchased the audio interface yet. Now I search the best for me audio interface, to record audio with sonar and hardware with in/outs and 2 phones outs like model - 18i8. Now I can record with 24 bit, 48kHz, 64 samples in and out, total roundtrip 128 samples and 2.7 ms with ESI Maya44e. Do the RME and MOTU can be like ESI and have same latency performace or USB interfaces all slower?