First, you grow in a windowsill, which usually has lower humidity, so plastic would be better if your humidity is low.
Lower humidity means you have to water more frequently.
The fact that your plants are in a windowsill means that you have to let them drain before putting them back in their place.
If you have low humidity and clay pots, then watering will become much more of a chore when it comes to repotting.
Clear plastic pots help you to see the moisture in the pot BUT if the pots are getting hit with any direct sun, they will heat up like a greenhouse, so if you use clear plastic, it's a good idea to just set them in another pot or wrap them with tinfoil or something.
The best thing I can think of is to get a plastic and a clay pot in the size that your plants will be in and fill each one with the same kind of medium they are potted in. Water these pots and see how long it takes for them to dry out. You will want them to dry out in about 3 days. Remember that this new potting medium will dry much faster because it is new, so when it is older, it will dry out more slowly. So if the medium takes 5 days to dry when it is new, it will stay wet too long after it is a few months old.

I hope that helps. You will find that what works best for one person will not work for another because there are a million factors that are different from one persons environment, watering habits, etc.