Graduated borosilicate beakers - they're easy to clean and are impervious to darkroom chemistry.
The 50 ml beaker is ideally suited for measuring out small volumes of liquids. I find this size particularly useful for flowing developer directly onto the plate.
The 250 ml beaker is a very handy size for mixing developer, and preparing the sensitizer for salted collodion. I don't think you can have too many of these lying around the darkroom!
The 600 ml beaker is a great size for mixing collodion formulas. The 1000 ml and 2000 ml beakers are ideally suited for measuring and mixing larger volumes of liquids, such as mixing up a new batch of silver nitrate.
All beakers are borosilicate glass and are easy to clean and impervious to solvents.