What airlines should I pick?

Hello everyone! I will be going from Mumbai to Frankfurt (Germany) for my Masters next month. I wanted suggestions as to what airlines I should pick.

Initially I had considered flying by Air India but when I called their customer support to confirm the baggage allowance, one said you cannot carry any free additional baggage as the weight concept is in pieces and not kgs or something like that. Another said you can.

I'm so confused. Has anyone else travelled with this airline? Will Qatar or Etihad be a better option ?