Best Multi-disc player/transport with AES/EBU out?

Well, the CL-10 has both (aes/ebu & co-ax, and it also has ST/ATT glass as well. I'm quite happy with mine used as a transport via the AES/EBU output feeding a Classe' DAC run balanced to a VK3i/Dna 1 Rev B.

Also, best changers with coaxial out?

I don't know how serious you want to get but for a big changer, 301 disks, the Pioneer Elite PD-F27 has a coax digital out. I got one about 2 weeks ago. Combined with an EVS Millenium II DAC, the sound quality is exceptional. Probably (maybe)not as good as a single disk transport but for the convenience, probably hard to beat (just my opinion). I was using a Pioneer PD-F1007 that only had a Toslink digital out. I ran it through a Digital Director to convert it to coax, then to the EVS DAC. The Pioneer Elite changer was definitely a big improvement. I'm not aware of any other mega changers with a coax digital out. The Marantz does not have one even though their website says it does. I had one and it does not.