I mean a second Lianna is more versatile than either Horghall or Elkanen, but if you want a green tank, you could do worse than Elkanen.
I think it also comes down to whether you have a better hero who’s called dibs on the cleric or druid tokens.
Elkanen is pretty solidly in the camp of “eh, he’s alright” and can do a bunch of things adequately. He’s best at tank or wing in war (where field aid can make him real hard to dig out), and as others have said, he becomes a royal pain when his emblems are up.
But if you have better options for the class tokens, a 2nd Lianna might make more sense.
There are a lot of heroes that perform tank better than Elkanen, but Elkanen is more versatile than Horghall. Having a duplicate hero, even of an amazing one, is a bit of a letdown, I agree, but Lianna still makes the most sense unless you really need a green tank for some reason.
I mean I have the opposite problem. I pulled a second Elkanen from my TC20.
Edit: I also agree with @l2ider. Halloween and Kingston are next month, so if you’re thinking if making pulls, you might want to wait. I just got my 6th tonic recently, but I’m going to try for Evelyn mostly and Kingston due to my EHT backlog, and currently I only have a Kadilen waiting in the wings which is not a compelling argument. Up to you if you can wait.