Thank you for your question.
Perhaps, you should take a lesson with a native speaker of English on Italki?
Then, they could explain these forms more clearly to you.
Who is the one I love the most (of all)? I love you the most (of all).
Truncated by natives as 'I love you most'. But usually, I would say "I love you the most'.
Who do I like the most (of all)? I like you the most (of all). We are best friends.
I like you most. Again, usually, I'd say 'I like you the most ('of all' out of the bunch).
It's not necessary to understand grammar to such a high-level to speak English correctly.