This question made me curious (I have always been into radios) and I googled around some more.
The Panasonic RF-2400D seems expensive for a super-basic radio ($27 to $32 US online), but 13,000 Amazon reviews give it an average 4.5/5.0. It is mono only, so if you want stereo music with headphones, this is not for you.
Whatever you get, I recommend something that uses standard batteries (AAA, AA, C, D, etc.) More and more models now come sealed with rechargeable batteries, which have a limited life.
Also, don’t store the radio with power cells inside. I think we’ve all opened an old device to find acid-encrusted batteries. Since you want this for “when the lights go out”, keep it battery-free with a stock of fresh batteries alongside.
If you use the radio regularly, change the batteries every year. One good strategy is to change all your batteries on the same day – start of Daylight Savings, January 1st, whatever. This applies to smoke and carbon monoxide detectors, too.