I've bought a number of tubes from Tube Depot. They were good to deal with. Also bought from Viva Tubes, but not NOS tubes. They were good to deal with.
I know you said that you won't use ebay, but that's where I purchased most of my vintage tubes. No issues. I only buy from sellers that regularly deal in tubes and they test the tubes. All had excellent feedback.
I did buy a bunch of vintage Mullard M8080 from an eBay seller in the UK. I got a noisy tube and he replaced the pair for free. This was before the tariffs....

