2 bus services that are the best between Sangli and Pune is either the Shivneri or Konduskar. Now Shivneri runs 3 times: 6:30 am, 11:30 am, and 5:30 pm. Konduskar is suitable if you want to leave late night, I took the 11:30pm bus and reached Sangli at 4 am, giving enough time to sleep for a while and freshen up before the start of the day.
Konduskar has comfortable seats with a friendly staff. No movies were shown on the way and though the plug points were available not sure about their working condition as I didn't try them. No amenity like food, water, blankets were provided so you should be ready with your own arrangements for them.
For travellers, please make sure that you do call the travels and check on the arrival time at the boarding point so that you make it on time. Also, no need of ticket print-out as they accept mobile tickets which you will get if you book it online.