Formal:
* J'aime beaucoup... (I like it a lot...) - This is the most common and neutral way to express liking something a lot.
* J'apprécie beaucoup... (I appreciate it a lot...) - This is slightly more formal than "j'aime beaucoup" and emphasizes appreciation.
* Je suis très attaché(e) à... (I am very attached to...) - This emphasizes a strong emotional connection to something.
Informal:
* J'adore... (I love...) - This is more intense than "j'aime beaucoup" and implies a strong liking.
* J'aime vraiment beaucoup... (I really like it a lot...) - This is similar to "j'aime beaucoup" but emphasizes the intensity of your liking.
* Je suis fan de... (I'm a fan of...) - This is a more colloquial way to say you like something a lot, particularly if you are referring to a person, a band, or a particular style.
You can also use adverbs to modify the intensity of your liking:
* J'aime énormément... (I like it enormously...)
* J'aime passionnément... (I like it passionately...)
* J'aime à la folie... (I like it madly...)
The best choice will depend on the situation and your relationship with the person you are speaking to.