Presta valves will lock closed and can be easily cleaned before inflating - schrader valves can suffer from unseen debris preventing a good seal and so should be used with a dust cap. Some people don't like dust caps...
You'd still need a dust caps with Presta as corrosion can cause the valve to stick (especially in winter).
@edscoble started
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Presta valves will lock closed and can be easily cleaned before inflating - schrader valves can
suffer from unseen debris preventing a good seal and so should be used with a dust cap. Some people don't like dust caps...