Dual purpose are what most heritage breeds are because small farmers needed hardy birds that provide both meat and eggs. Layers are lean, not much meat but produce lots of eggs. Ornamentals are pretty to look at, period. Few ornamentals lay eggs very well, and aren't usually very meaty. They're kinda nice to have around though, eye candy IS nice!
Sex links are usually good layers, but lighter and are getting away from true dual purpose type IMO. They are cheap and easy to find and great layers though.
Buckeyes are great for winter because of their small combs and are good sized so they are fairly meaty... but they are not the very best layers. (still one of my faves though)
Rhode Island Reds are large as well, better layers, and ok in the winter but because they have largish combs, they can get into a little trouble in the winter. (always good birds though, usually worth the small risk)
Chanticlears are nice and large, bred for winter, and I 'think' pretty decent layers, I don't have personal experience with them though I'd like to try them myself one of these days.
Barred Rocks are also reccomended as has been said.
All this is why I like to have a mixed though not TOO mixed flock, variety will keep all your bases covered, but keeping them to a similar type means you don't have to make drastic accomodations for too many extremes of variaty if that makes sense.
Here's the best chart I know of when considering breeds vs needs, look it over, and see what you think. When you have decided on some possibilities, you can ask or look up particulars.
http://www.ithaca.edu/staff/jhenderson/chooks/chooks.html