I have this Tung Sol one that a lot of people seem to enjoy. It’s great for providing more of a classic tube sound (darker, more distortion, and can help to neuter sharp treble). I just prefer the PSvane tube as it has better bass extension and less distortion without sacrificing any detail in the treble. Still retains a nice, warm sound but is much cleaner than a lot of people look for in a tube. It sounds more like a class A solid state than a traditional tube amplifier.
Oh and I have this preamp tube as well that I’m not using:
https://www.amazon.com/dp/B01HQZ27UW/ref=cm_sw_em_r_mt_dp_b71FFbN7HJNDH
If you’re interested, I could sent it to you for no charge! It’s a nice little tube but I just preferred the other one I went with. It’s already been burned in!