We have used lots of different S.D.S drills. The first, used in the Scaleburn dig was a 24 Volt Bosch. We adapted it it to run on rechargeable NiCad batteries to give us extra power.
We currently use 3 different ones. The first is a modified Dewalt- a 24 Volt, using a twin sealed lead acid pack.The second is a 36 Volt Lithium ion Bosch. The third is a 36 Volt Hilti.
All have some drawbacks. The Hilti will give the longest capacity but since the large Lithium ion batteries are not completely sealed I have reservations about taking it into a wet environment.
The Dewalt is heavy with it's pack but is extremely reliable.
To my mind the best is the 36 Volt. Bosch with the larger amp hour capacity and for most purposes is our first choice.
Incidentally you can also use petrol S.D.S. Drills in a well ventilated environment.! At the present time we have two!