Coffee. I enjoy various kinds of tea (both herbal and caffeinated), but I don't exactly drink it the same way I drink coffee.
I've tried switching to a caffeinated tea as a coffee alternative because I did want to cut down on caffeine. My plan was to cycle through a few different types of teas over a period of months to slowly wean on caffeine content, but the ritual of having a strong flavorful drink is something I enjoy too much and no tea I've tried comes close to coffee. Nothing beats a strong black coffee.
Assam and chai are the closest I've gotten to having a tea that I felt confident I could replace with coffee just based on flavor. I also like matcha, green tea, white tea, etc, but those aren't coffee substitutes for me. The problem is that I just really enjoy the taste of coffee. I find that I tend to feel more hydrated if I drink tea as opposed to coffee, so there's a certain feel-good aspect. But to be honest I just let my mood dictate what I primarily drink.