hhmmm...good question. i think something in nylon is good (like hamptons) although i find in the snow, leather is best. leather should b ok in the rain too if it is weather-proofed. i just wouldnt use anything signature
I agree with the Hamptons nylon line. Those are super easy to keep clean and pretty much waterproof.
Hamptons pebbled leather and chelsea pebbled leather works fine for rainy days. I would use the Vintage Vachetta leather such as in the Ergos. I have these and when it rains, no spots are left. The handbag dries up just like new. I would not use that Legacy leathers as water spots form and they do not come out. You can use any of the Coach Classic leather bags. These bags dry up as new. The Ergo leathers from this year are the glove baseball leather of Coach from yesteryear and these dry up just fine. The Dooney & Bourke All weather leather is great too for rainy days.
I use my signature in the rain and snow here in NY and have NEVER had a problem! I ONLY own signature really except for 2 older leather bags! The signature is VERY easy to care for, and w/ 2 children, I need easy!!!!!! LOL