NOS EL34 Non- Mullard

I have been considering adding a final Quad of NOS EL 34 for the long haul given the growing scarcity of these tubes.

I do not want to spend " Mullard" dollars for the quad.  I have seen quads of Tesla Brown Base, Tesla Black Base, Siemens and Sylvania Fat Boys at less stratospheric pricing. I know this is a touchy topic but wonder which of the above would be the "sweetest" or even "warmest" sounding tubes?

Thanks in advance and please only constructive responses.