This is my standby contact form plugin. I've tried others and have found no reason to switch. There is a ton of versatility with it, to the point that I've created 140 question application forms and it handled it like a champ. As a professional web designer, this plugin has saved me countless hours and in turn, saved me a lot of time, and as you know; in this business, time is money.
It's not quite as user friendly for the amateur, simply because it allows for so much customization and those that aren't HTML/CSS savvy won't be able to use all of the features (such as class handling, etc), but if you use contact forms a lot and know what you're doing, I highly recommend this plugin!