Gore-Tex, Foulies, Drysuits
I agree with others that state Gore-Tex is your best bet for "breathable" duds. That being said, Gore-tex membrane fabrics only work well as longs as the water beads up on the outer fabric. If the Water-Repellency is worn away, the outer fabric becomes soaked, the vapor passing through the gore-tex becomes trapped and condenses and maakes you feel clammy. Also, you can over saturate the gore-tex with perspiration if you really exerting yourself.
If you plan to be an all-weather sailor, gore-tex is the way to go as long as you keep up the water-repellency. If you plan to do mostly fair weather sailing and just have foulie gear for the "just in case" scenarios, gore-tex is pretty over kill. You can get ALMOST get as effective breathable rain wear for light rain with a good tight woven outerfabric and good water-repellency and it will be more breathable as long as the WR is maintained.
As far as drysuits, I think they are great and they are not more expensive that a set of medium to heavy weight foulies. The added benefit is that a dry or good semi-dry suit offers immersion protection if you fall over in cold water, whereas a set of foulies won't. I often wear one when I singlehand my boat in May and early June weather while the water is still below 60.
Drysuits are heavily worn by kayakers, especially here in the Northeast during fall, winter, and spring temps. in case of immersion as, when properly layered underneath, they can keep you alive in 40 degree water for several hours. They are not only comfortable, they can keep you warm and are windproof. Companies like Kokatat, Stohlquist, NRS, and others make excellent dry and semi-dry suits at often lesser prices than "sailing" specific ones.