Formal:
* J'aimerais: This is the most common and polite way to say "I would like."
* Je voudrais: This is another polite option, slightly more formal than "J'aimerais."
Informal:
* Je veux: This is a more direct and informal way to say "I would like."
* J'ai envie de: This means "I feel like" and is used to express a desire for something specific.
Examples:
* J'aimerais un café, s'il vous plaît. (I would like a coffee, please.)
* Je voudrais un croissant, merci. (I would like a croissant, thank you.)
* Je veux une glace. (I want an ice cream.)
* J'ai envie de pizza. (I feel like pizza.)
Remember that the choice of phrase depends on the context and the relationship between the speaker and the listener.