Informal:
* Pleins de bisous: This is the most common and natural way to say "lots of kisses" in a casual setting.
* Des tonnes de bisous: This translates to "tons of kisses" and is a more exaggerated way of expressing affection.
* Gros bisous: This literally means "big kisses" and implies a lot of kisses.
Formal:
* Beaucoup de baisers: This is the most formal way to say "lots of kisses" and is often used in written correspondence.
Other options:
* Un tas de bisous: This literally means "a pile of kisses" and is a playful way to express affection.
* Des millions de bisous: This translates to "millions of kisses" and is a very affectionate and exaggerated way of saying "lots of kisses."
The best translation will depend on the situation and the relationship between the people involved.