1. Добро пожаловать (Dobro pozhalovat') - This is the most common and formal way to say "Welcome" in Russian. It literally translates to "Welcome well." It's suitable for a variety of situations, such as greeting guests at a hotel, a store, or a formal event.
2. Здравствуйте (Zdravstvuyte) - This is a general greeting that can be used to say "Hello" or "Welcome." It's a less formal greeting and is appropriate for everyday use.
So, the best way to say "Welcome" in Russian depends on the specific situation and your relationship with the person you're addressing.