I'm honestly not very picky with tea, to the point this is a hard question.
I grew up on southern sweet tea, where the flavor of the tea itself is definitely secondary, and it has a big soft part in my heart. That would make me pick black.
But spending some time in Japan taught me about the goodness that is iced green tea, and I love matcha flavoring so perhaps I should pick green.
And for hot tea, I once had this great "English breakfast" that was actually nice and malty many years ago and loved it. However, I think that may have been a particular definition of that tea that doesn't match other ones. I've not refound that flavor, but it'd be my choice. Which I guess makes it another boring black tea.
Ooh and mate is great too, especially in replacement of caffeine. And some roiboos. And white tea. I was hard on tea for a few years but kind of fell out of it more recently.
This is the problem with me, I'm incredibly indecisive and prone to see upsides and downsides in everything.