Decaf tea doesn’t quite taste like normal tea ... there is a strange after taste which takes some getting used to.
Another problem is the decaffinating process which isn’t very healthy. There are a few possible processes but the common one uses carcinogenic stuff. Clipper decaf tea is the only one I know which does not use this process but it is far from cheap.
I now drink herbal teas most of the time. I know they are not tea and I don’t pretend they are but there is a huge variety available. Strangely, I used to be happy to drink the same tea 4 or 5 times a day every single day. Now I drink 3 or 4 different herbal teas each day and once or twice a week spice it up with a cup of good quality caffeinated black tea.
I very rarely drink other caffeinated drinks. I have never liked coffee. But when I am very tired or have a long day ahead of me, I will have a single glass of coke. As I drink so little caffeine this really perks me up. If I drink a glass of coke at 6pm, I am still buzzing at 1am.
I guess this is a long way of saying I think the options are to either get used to the flavour of decaf tea (and be aware of the side effects) or try to find d something else you like.