Is it just me or are energy cells basically useless? Of course, they can be used for pistols and things like that, but those guns are very weak compared to many others in New Vegas. So are there any genuinely good guns that use energy cell ammunition? I know many guns use microfusion cells, but those are fairly rare.

The beauty of energy weapons is you can freely convert ammo between types. Best gun running on e-cells is Plasma Defender which is comparable with .44 revolver. Also Pew PEw and Pulse Gun use those but that's much later in the game. Convert them to whatever you need.

You can convert those E-Cells directly into MFCs at a workbench, so they are not useless and worth picking up.

Go find Pew Pew and the Pulse Gun then come talk to me.

Plasma defender for the win!

Pew Pew and Pulse Gun, as previously mentioned. Also, the regular laser pistol is the energy weapon holdout.