The type of grinder depends on the method you are using to make coffee, and of course, your budget.
The main problem that can occur with coffee grinders is a build up of heat which breaks down the aromatic compounds in coffee, so a good quality grinder should be chosen.
If you are making filter coffee you don’t need anything that can grind coffee exceptionally finely and you probably won’t experience a heat issue, however if you are grinding coffee to make espresso, it’s worth investing more money as espresso requires an extremely fine and consistent grind, a coarse or less consistent grind can reduce the quality of the finished coffee.
A burr grinder should always be chosen over a blade grinder, as the blade grinders are more prone to heat build up and less consistent.