Best Stonehenge Tour from London

Golden Tours (Gray Line) does a good trip. Stonehenge and Bath:
https://www.goldentours.com/stonehenge-and-bath-tour-from-london

If you want to do Bath, Stonehenge, and include Salisbury while you are out, there's this tour:
https://www.goldentours.com/bath-stonehenge-and-salisbury

Golden Tours are on a nice coach/bus, and they pick up at several hotels around London and at Victoria Station.

Another company which does great day trips out of London is the London Walks Company.
www.walks.com
No need to book. Just turn up at the designated meeting place in the right tube or train station. Your group leader will meet the group there, and you go by train to your destination. The group leader is your tour guide, and stays with you the whole trip. Train back to London.

I did Stonehenge using London Walks. www.walks.com. They combine it with Salisbury. It goes once a week through the summer, less frequently in winter. Glad I've "done" Stonehenge, but that's about it - not my thing.
Katy.

We also used London Walks. We met the tour guide at Waterloo train station and the group took a train to Salisbury where we toured the town and cathedral. We then took a coach to Stonehenge and toured the grounds. We then took another train back to Waterloo. Very well organized and informative.