Largely owing to convenience of supply, I’ve made my last few builds with Russian triodes instead of Western ones. These are in plentiful supply as NOS from the 70s and 80s, and available cheaply on eBay and other sources. Typically these are military-spec and quite consistent in quality, so they are fantastic for audio.
Some of them are pretty much direct equivalents (eg. 6N2 for 12AX7, 6N6 for ECC99) while others are close but not quite the same, meaning any circuit would need to be recalculated if subbing in a Russian tube.
This is relevant because most tube audio schematics I’ve found on the internet are specified with Western types, some of which have no direct equivalent.
So to bring several sources of information together in one handy reference, I made a spreadsheet which lists the different tube types and their vital parameters.
To make things easier I made it into a table so you can sort and filter it in Excel. You can download the original file here