Modding an old Ryobi ONE+ 18v light?

[Galane]

I've tried a few 18V LED bulbs that directly replace the incandescent in an old blue Ryobi ONE+ flashlight. So far they're all just as bad or worse than the stock bulb. I'm looking for something that can do a bright (as in a heck of a lot broghter than the wimpy original bulb) and even flood.