Opinion: what to pot seedling up into?

[babice]

Do you have a method you swear by? Do you use say 4 or 6 inch plastic pots to pot up tomato seedlings in potting soil until they're ready to be planted outside? Do you use peat pots? Is there some other method you use? For example, I read a suggestion by someone to use the 16 oz plastic drink cups with drain holes in the bottom. Some have said use plastic 2-liter bottles or cardboard 1/2 gallon juice cartons.