This is also grammatically correct.
According to the rule of Subject - verb agreement, the verb should agree with the subject,not the complement.
(Not a teacher)
According to Michael Swan "Practical Usage" p. 62, 'the' can refer to the whole family of the thing:
The tiger is in danger of becoming extinct.
(The sentence is about the whole tiger family, not about individuals).
Then how about this sentence?
I love the tiger the most. (refer to the whole tiger family).
However, with reference to your suggestion, it is usable in the form: Of all the animals in the jungle, I love the tiger the most OR My favourite animal is the tiger.
With reference to your question about the panda - the same applies: I like the panda best of all animals >> My favourite animal is the panda.