Question

I don't like poetry, but there is … poem I've really enjoyed.

Answer 1

There's one poem I've really enjoyed

Answer 2

Лооооол, честно, задание некорректное, но лично я бы отметил два варианта, как можно ответить.

1) ... but there is one poem I've really enjoyed.
2) ... but there is the only (единственный) poem I've really enjoyed.