Plain honeybush is very cheap, naturally slightly sweet, re-steepable, great hot or iced, & basically can't be over-brewed. Were I seeking decaf, I'd drink it all the time. Rooibos is a relative with a more mineral-woody profile, also doesn't contain caffeine. Peppermint is also cheap & effective even in very small amounts at making water less boring. None have the tannic bitterness that complicates true tea.
Actual tea is delicious, but costly, so when all I want to drink is "pleasant aromatic liquid," which may be what you're really asking for, I don't waste tea-money. Green tea does still contain some caffeine if you're actually trying to avoid that but bulk quantities of gunpowder & sencha are often least costly. Loose leaf saves a lot of money & waste (just throw it in the garden, it's wet leaves.)