Raingear, the outermost and one of the most important layers, which protects you from the elements.
I’m using a Norrøna Falketind Gore-Tex Jacket which is very sturdy thanks to its three layer construction. Furthermore the jacket has a lot of waterproof zippers in terms of temperature regulation so as a big hood that can be worn over the helmet.
When choosing rain pants for cycling, be sure to chose a big enough size! Rain pants which are too tight bother you while getting on and off the bike and feel uncomfortable when riding. I’m on the way with a pair of Gore Gore-Tex active pants.
Water-and windproof overshoes are protecting my shoes / feet against cold winds and rain. While cycling in milder winter climate (up to -10 degrees) I combine my Gore Gore-Tex overshoes with a pair of gore-tex hiking shoes.
Does not necessarily help against the rain but to be seen during rain and in bad weather!