Since you post in the Android forum, we can't recomment Apple, Blackberry and Nokia, since those don't have Android. But if you had posted in the iPhones forum, we could only have recommended an Apple iPhone.
So it's all up to you. Things to start with:
1. See what your friends and colleagues use as a business phone.
2. Get a clear list of your requirements.
3. Define the future use, so you can chose the right subscription.
4. Decide between a subsidised and an unsubsidised phone.
5. See what is offered that matches point #2, #3 and #4.
I am Jaydeep Biswas. By profession I am engineer. I am planning forward to buy a new business phone. I need suggestion that which one among Samsung galaxy, Apple, HTC, Blackberry and Nokia phones. Please suggest the model number you find best.