Well...... guess what? I would recommend a nice strain of English Cuckoo Marans (surprise, surprise) But then if I didn't think they were great I wouldn't have kept them for over 25 years!
So those should do the brown eggs for you. And recently I have started with Cream Legbars for their blue eggs and I am very pleased with those also they are good layers even in this dark weather without extra light, plus Higgledy Harriets for speckled brown eggs and Olive Eggers for green.
They really make for a lovely mixed egg box