As with everything, you get what you pay for with grinders.

$: Plastic grinders are perfect for temporary measures, or something you are okay to lose. Typically only in 2-stages, you will need something to knock the cannabis into.
We recommend plastic grinders for vacations, parties, or group settings. Use for weeks, sometimes months.

$$: Wood or polished raw aluminum options at this price point. Wood is a really retro option and usually has pegs instead of teeth. We prefer the diamond teeth of the aluminum options, they give a more consistent grind. The pegs sorta tear, and the wood gets gummed up easier. Aluminum is generally easier to clean and maintain. Last month to years with occasional to moderate use.

$$$: Electric grinders are the next on the list. These tend to be more expensive than some of the aluminum options. They look and function similar to coffee grinders.
However because of this, the grind can be very fine and a lot of trichomes get knocked into the lid. These are accessible and perfect for people with dexterity issues. These last for years with moderate use.

$$$$ Premium aluminum or titanium plated grinders are the most expensive. Will a less expensive one do the job? Sure. But for how long? Premium grinders are perfectly engineered with the perfect grip, multi-directional cutting and sharp teeth to handle the stickiest of buds with ease. Scratch resistant, with a perfect grip. They are ultrasonically cleaned (instead of just raw aluminum being polished). At the ultra premium level there are only a couple recognized brands. These are a treat for regular everyday users who smoke a lot of weed. These also make perfect gifts for flower connoisseurs. These last a lifetime with heavy use.