Always direct travel is the best option. If you take Amaravati then you can enjoy Dudhsagar falls enroute just before MAO. But must be in AC. Also if you really wants more comfort then as per my opinion Take Pune Douranta from Howrah & from Pune take Goa Express to MAO. Waiting time @ Pune is only 4.5 Hrs. Also self travelled many times between Bangalore & Goa by KSRTC Airavata, avoid this as road condition is not very good in many stretches.