Hi I’ve been playing touhou games for over a decade and played every one, including the DOS games

EoSD is the first game in the windows era of touhou. So it is the literal starting point of everything else (DOS games aren’t really considered canon nor part of the normal touhou experience)

For gameplay, I would say eosd is a fine first touhou game.

If you want the fullest touhou experience right off the bat, start with Imperishable Night. Tooons of gameplay and one of the most customizable touhous. Its as hard as you want to make it for yourself.

Be warned that EoSD (original, not sure about remake) and the games before it do the bullshit inaccessible thing that arcade games used to go where you aren’t allowed to finish the game on Easy. zun cut that nonsense out after (good for him) but that’s context for you in case you get the older games.

My genuine recommendation to newbies is to either try the demos or “acquire” the game first, then to buy the game if you’re still playing after two hours. Because the games are very hit or miss depending on the kind of person you are. The demos often don’t do a great job of letting you know what to expect in the latter half (looking at you, UFO), so don’t discount the later option just because of a demo being available. (But nevertheless, if you try it and feel like this is the game for you, then give zun your money. He needs a beer after the work he puts in)