Informal:
* J'aime bien lui. (This is the most common and neutral way to say it.)
* Je l'aime bien. (This is similar to the first option but slightly more direct.)
* Il me plaît. (This means "He pleases me" and implies a stronger liking.)
Formal:
* Je l'apprécie beaucoup. (This means "I appreciate him a lot" and is a more formal way to express liking.)
More intense:
* J'ai un faible pour lui. (This means "I have a weakness for him" and implies a stronger attraction.)
* Je suis attirée par lui. (This means "I'm attracted to him" and is the most direct and intense way to express liking.)
Note: In Canadian French, the pronoun "lui" (him) is often used instead of "le" (him) when talking about someone in a positive way.
Remember that context is important, and the best way to say "I like him" will depend on the situation and your relationship with the person you are talking to.