I still refer to it as shampoo too..dont worry, lol.
The p21s is very nice and mild. I know its very popular with guys here.
p21s bodywork conditioning auto shampoo
I still use super slick n suds on a regular basis personally.
Super Slick & Suds - 32oz
Heres the citrus wash and gloss that blueone referred to (however, wont be back in stock for a few more days)
Chemical Guys Ctirus Wash and Gloss Auto Shampoo
Optimum is also an option.
Optimum Car Wash
Either way, I would suggest grabbing a 16 or 32oz size to start with to ensure you like it since some will create more suds, some will be stronger or more mild, etc. Once you try two or three different ones and decide you really like one, then it may be beneficial to move up to a gallon (as long as you wash often enough to warrant one).