Who is your favorite tube seller?

If for my Quicksilvers, no one is better than Mike Sanders.  For every thing else, it use to be TheTubeStore and then Upscale, so now down to one.  

For my Conrad-Johnson electronics I have learned the hard way to buy the tubes from Conrad-Johnson.

I’ve used a variety of vendors over the years, depending on their stock. Andy is really top tier in the U.S. but slow and does not handle certain tubes. He is the gold standard. Brendan Bievers was great but his stock seems to be vastly depleted. I think Tube Monger is now gone. I’ve bought some rare tubes from other audiophile collectors who were savvy enough to buy rare tubes when they were readily available. Now, things like real GEC KT 66 power tubes are pretty much impossible to find as never used; ditto GEC U-52 cup bottom rectifiers as NIB.

I run 6h30s in my line stage and finding early DR Reflecktors is nigh on impossible; they are counterfeited and many of those for sale are late production, which doesn’t have the mojo of the early production. 

I buy my amp tubes (except for the 12ax7) from Lamm. I can still get Dutch old stock tubes from Allnic for my phono stage main board (that’s where I use the vintage GEC rectifier in the power supply). 

So-called "NOS" is typically a "pull" and there is a difference-- a true, never used old stock small tube can last a long time- the pulls are good for a couple years, if that. 

If you find a reliable vendor, buy. These older tubes are getting harder and harder to source. 

I have had excellent results on ebay with many sellers but you have to be experienced, know your tubes and have a tube tester. Incredible deals can be had if you really know your tubes and spend time searching.If you are not experienced then Brent Jessee for used and Psvane for new would be my choices.  
The worst tube experience I have had was with VIVA TUBES.  They sold tubes they claimed were NOS with great test values.  When they arrived they were old, appeared heavily used and tested awful.  They did give me a full refund since I used ebay.  

Brent Jesse has been my go to lately.  He probably has one of the best NOS offering these days.  Upscale and Tube Depot are also good.  I’ve used Viva several times and only had to return once.  But they took them back and refunded me in full right away.  Anyone that has used tubes for a while understands you can get a bad tube from anyone, notwithstanding the testing they say they do.  I just got some new Summit tubes from PsVane and one went noisy after a week. And their new Summit line is suppose to be their best.  They are replacing them though no questions asked so again just goes to show you can get a bad tube from anyone at any time.