Formal:
* আমার সেরা বন্ধু (amar sera bondhu): This is the most common and formal way to say "my best friend".
* আমার অতিপ্রিয় বন্ধু (amar atipriya bondhu): This translates to "my most beloved friend" and is even more formal.
Informal:
* আমার ভালো বন্ধু (amar valo bondhu): This translates to "my good friend" and is more informal.
* আমার বেস্ট ফ্রেন্ড (amar best friend): This is the direct translation of "my best friend" and is the most common way to say it among young people.
Other options:
* আমার হৃদয়ের বন্ধু (amar hridoyer bondhu): This translates to "the friend of my heart" and is a more poetic way to say "my best friend".
* আমার আপনজন (amar apanjon): This translates to "my loved one" and is a more general term for someone close to you.
The best choice will depend on the situation and your relationship with the person.