Comment by bityard
Were the old Rayovac batteries alkaline or zinc-carbon? Zinc-carbon batteries use a "dry cell" chemistry that will never leak, have a low self-discharge rate, and are very cheap to make and buy. You typically find them marketed as "heavy duty." The trade-off with those are that they have a lower energy capacity compared to alkaline.
I use NiMH in almost everything but for things like TV remotes and clocks that sip power AND you can't be arsed to change them all the time, they work great. I buy a pack of 4 at the dollar store.
Alkaline. Rayovac spent a lot of money making alkaline that wouldn't leak (after several years of research one guy's wife asked "why don't you encase them in steel" - turns out that works, or at least that is how I heard the story). They never has the capacity of the more expensive competitors, but for my camping stuff I'll take that trade off. (all too often the last trip of the year I'm throwing everything in a box in the rain, and then it gets stored until next season when I'll just put new batteries in if needed)