There have been lots of excellent insights here, but there are just so many variables such as commute distance, normal riding attire, bike setup, and typical rain weather that it's difficult to make generalizations.

I've had lots of different rain gear over the years, not so much because the pieces wore out, but rather because my needs changed as I moved from college and through different jobs. Sometimes I didn't care about getting a little wet and had short rides, while at other times I had nicer clothes, longer rides, but changing facilities at work. Still at another point in my life I had dress clothes, shorter rides, and didn't want to change at work.

Each situation has it's own best answer in terms of gear, and smart money buys a solution that's best suited to specific needs.

That said, for me nowadays it's a rather pricey Marmot "pack lite" type of parka with a hood to go under the helmet, and REI brand waterproof coated/lined nylon windbreaker type pants along with Totes rubber overshoes and either a waterproof over-glove for winter, or a light glove like Mechanix or Answer BMX just to chase the chill. It all stows easily, dries quickly, and is suited to my 2-3mile journeys in often cold, heavy, Michigan rains.