I wouldn't worry about language-level support at the moment: there aren't as far as I know any mature implementations yet, and even if there were libraries are usually better for learning purposes.
Personally I would recommend Haskell. Native row types are coming "eventually" and always will be, so there's some ceremony involved, but it's the ecosystem with by far the best alternative solutions to the problems algebraic effects are supposed to deal with: idiomatic javascript can make any programming discipline look good, whereas it'll be much more illuminating to compare algebraic effects to a more traditional `mtl`-style approach.
Personally I would recommend Haskell. Native row types are coming "eventually" and always will be, so there's some ceremony involved, but it's the ecosystem with by far the best alternative solutions to the problems algebraic effects are supposed to deal with: idiomatic javascript can make any programming discipline look good, whereas it'll be much more illuminating to compare algebraic effects to a more traditional `mtl`-style approach.