Formal:
* Ласкаво просимо! (Laskavo prosymo!) - This is the most common and formal way to say "welcome". It literally means "Welcome please!".
Informal:
* Вітаю! (Vitayu!) - This is a more informal greeting that can be used to say "welcome", "hello", or "greetings".
* Добро пожаловать! (Dobro pozhalovat!) - This is a Russian phrase that is also commonly used in Ukrainian. It means "Welcome!".
You can also use specific phrases depending on the situation:
* Радий вас бачити! (Radyy vas bachyty!) - "Glad to see you!"
* Приємно познайомитися! (Pryjemno poznajomytysia!) - "Nice to meet you!"
* Здоровенькі були! (Zdorovhen'ki buli!) - "Welcome! May you be healthy!" (This is a more traditional greeting)
The best way to choose the right phrase is to consider the situation and the level of formality.