I've got a $10 OLIGHT I3E EOS (black) that I carry every day on my keychain. 90 Lumens, about as big as a AAA battery (which is uses), twisty. I love it. Always have it on me, surprises everyone with how bright it is.
I also bought an $8 BudgetlightForum 348 (
https://us.gearbest.com/led-flashlights/pp_554387.html?wid=1433363#goodsDetail) which also has a keychain hole, push button ON/OFF, roughly the same brightness as the olight (Nichia NVSW219BT), but a little bit longer. It doesn't go on my keychain, but it's a nice little light to keep in a drawer or glove box. It's a little too easy to press the button and it's a little too long to go on my keychain, but it's also really nice.
Both lights can take a 10440 battery to hugely pump their brightness, at the cost of battery life, if you want. 90 lumens is really bright though.