I don't think you can do better than Andy at Vintage Tube Services. His attention to detail when choosing tubes is unmatched IMO. He's not always fast to fill your order, but when you get the tubes, they are going to be impeccably matched and microphony/noise will be screened so the tubes are appropriate for their intended application. Unfortunately, he's soon to be done with the tube business and will be moving onto new ventures. Brent Jesse Recording also enjoys a good reputation, as does Upscale Audio. If you want new production Russian stuff, RAM Labs sells very carefully chosen and matched tubes. There are a lot of people who make claims that aren't true with regard to being NOS, matched, etc. Buyer beware of many sellers.