Presumably we are talking about AA and AAA batteries, which makes us pretty much dinosaurs in terms of cutting edge battery technology. Lithium ion batteries, 18650, 14500, and the like, offer some real advantages in terms of capacity and reliability. They also offer snares for the unwary,so one must learn a bit, take precautions, and follow good practices.
I have a Zebralight headlamp that uses 18650s and it is the best headlamp I have ever used, and I will probably acquire more in the future.
One aspect of rechargeables, either NiMH or lithium ion, is their cheaper cost over the lifetime of the batteries. This is rather significant, because I find that a lot of my "precious" run on batteries, and more are on the way.
I also own a solar panel, and have the ability to charge my smaller batteries with nothing but the sun. That could be handy sometime.
Geezer in Chief