looking to use a cup

so I've never had a cup. I use tampons and always have to use the super plus ones by kotex except for the first and last days I can use regular. I have been wanting to try the cup but they are expensive and I don't want to buy one and hate it or buy the wrong one. any tips on which one I should get? and how i know which one will work right? also how do they work? are the uncomfortable? Do they feel weird when you sit down?