I replaced my D-cell Maglites first with a 2xAA LED flashlights and now a 1xAA or 1xAAA depending on expected need. The 1xAAA LED lights these days have a lot of output. For times when I need a lot of lumens to reach out, I have a couple LED lights which use 18650 Li-ion batteries, still way smaller and lighter than even a C-cell maglite.

My old Maglites have been retrofitted with LED emitters and rechargeable batteries. With LED emitters, D-cell alkaline batteries will time out and leak before they run down from use. Maglites will always be reliable blunt instruments and now the bulbs won’t fail due to impact damage.