For those of you who are looking to start buying reusable drink containers, here's a piece of advice: wide neck opening.
This is actually a thermal food container, but I find standard drinks containers difficult to keep clean, even with a bottle brush. This solves the problem, making cleaning a breeze as my hand fits inside. I'm not saying to go and replace your currently reusable containers that still work, but it's something to consider when it comes to buying new ones.
A side note, I have never had any problems having drinks in my own containers from @mrbeansg Bravo!