Formal:
* Welcome: (English)
* Bienvenue: (French)
* Willkommen: (German)
* Benvenuti: (Italian)
* Bienvenido: (Spanish)
Informal:
* Hi! (English)
* Hey! (English)
* Welcome aboard! (English)
* Nice to meet you! (English)
* Hola! (Spanish)
* Ciao! (Italian)
Other ways to express welcome:
* We are delighted to welcome you.
* Please come in and make yourself at home.
* It's a pleasure to have you here.
* We're so glad you could join us.
The best way to say "welcome" is to choose the phrase that is most appropriate for the situation.