The ponchos look really comfy, but frankly, ponchos make me look like a pup tent on the move -- and wearing a baby underneath doesn't help!
We have the Suse's Kindercoat and LOVE it. The sizing is fairly generous -- I am 5'4" tall and a size 8 - 10 and my babysitter is 5'10" and a size 12 -14 and it fits us both well. (I bought a medium) What I especially like about it is that you can take out the lining and use it as a raincoat year round -- wonderful for days when you don't have an extra hand for the umbrella! Also, the pockets are huge, so there's room to tuck in wallet, keys, water bottle and a couple of diapers, so you don't have to carry an extra bag.
I have the original version, where the lining isn't really finished, so you wouldn't want to wear it on its own, but the model that's on sale now has a lining that can be taken out and worn as a separate fleece jacket, which is a nice feature.
Also, it's a great price!