I personally do not like Nectar as it is VERY foamy when shaken and has always drys out my mouth when drinking it and it has a weird metallic taste, IMO. However, I think the best WPI's are GF-Pro (Orange Cream, Blueberry, and Rasp. Lemonade), I-Pro (Rasp Lemonade; same as GFpro without SDBP), Dymatize Iso-100, and NOW WPI.
On another note, Syntrax is suing a handful of the bb.com forum members for voicing their opinions on their products so I choose not to support a company like that, even if they have a good product or service. I also choose not to support bb.com because the mods are a-holes and the CEO is a douche-rocket.....