I started with TNG. But now I have come to realise that TOS is the best of the shows. It's more ...fun, and less preachy. And TOS didn't set out to make a 'Star Trek' show, but just good sci fi, like the Twilight Zone. It didn't get bogged down in canon.
I have all 6 shows including TAS, on DVD. And all the movies. But I acknowledge a huge debt of gratitude to TOS. Without it, the others would not exist. My age? 30. I started watching Trek around '94 when I was 12