These days the choices are many: the standard egg timer (sand timer), electric toothbrush with built in timers, phone app timers, kitchen timers and now a Two Minute Turtle Timer.
The best thing about a sand timer is it's usually free from a dentist. The down side is it is easily knocked off the sink/tippy, it gets lost quickly, it does not have quarterly indicators, and it doesn't keep the attention of many kids.
There are different varieties of electric toothbrushes. The plus side of an electric toothbrush is it has a built in timer for 30 seconds each (usually) and the vibrating head helps with the brushing. The down side is it's pricier than the rest and the heads need replacing every 3-4 months. For some children the electric sound in the mouth is too loud and for some adults (like me) it contributes to tinnitus.
The phone apps are many with games, dancing Elmos with singing. The plus is it's exciting and keeps kids' attention and they break up the 2 minutes into 4 even parts. The downside is 1) the parent needs to have their phone in the bathroom--it's not waterproof,. It's not shatterproof. 2) the phone can be a source of distraction for other things, 3) it requires downloading an app.
The kitchen timer is a little dry for most children-- count down 2 minutes either digitally or with a ticking.
The Two Minute Turtle-- the plus is the kids own it. They can hold it in their hand and enjoy pressing an actual physical button--it is designed for kids. It's safe- no risk of breaking or getting wet. It has LED lights so it's attractive and has enough to watch to keep attention without distracting them. It is intuitive--no instructions, simple, follow the lights. It has a random start so a subtle game element (which one will be the first to blink?). It is both cute and techy with the unique turtle circuit board. kids can take it with them when they go on a trip. It is designed to last 3 years if the user presses the button twice a day. It both sticks to the mirror and it's portable. Kids can take it with them on an overnight (and they do)> The downside? no sound.
This is a first-hand account from my experience as parent and toothbrusher. It's true and it's not objective. What's your experience with toothbrush timers? I look forward to hearing! Email me, firstname.lastname@example.org