Tea has caffiene too, which is why it's addictive. It usually has less than coffee, but it depends on the variety. I read somewhere that coffee can help stave off the effects of dementia, though its' been a while so I'd have to go hunting for the article. Caffiene can help people with ADD or ADHD as an alternative to ritalin. Tea has antioxidants, more in green tea and white tea than black tea.
Personally I prefer tea. I enjoy fancy flavoured leaf tea but even just bag tea can make a decent cuppa, so in that respect tea is superior to coffee since instant coffee is usually terrible compared with ground.