We find the quietest and most romantic restaurants to be V&A, Shula's, Citricos, Artist Point, Jiko and bluezoo. They are all more expensive, V&A being the most ex*****ive, followed by Shula's and bluezoo, then Jiko, Citricos and AP. The only signature I really wouldn't suggest for a nice romantic anniversary meal is CG. It tends to be the loudest and most kid-friendly of the signatures. It is worth going to, but not for a nice quiet romantic anniversary meal.
As the PP said, everyone is going to have different opinions on their top 10's. For example a lot of people have 'Ohana, Coral Reef and Le Cellier on their top 10's but we personally find those three restaurants awful and overrated.
As far as where to start with other ADR's, you have to decide what sort of dining experience you want (character meals, buffets, signature meals, other TS meals). Then check out a site like allears.net. They have menus from all the restaurants on property to give you an idea of what they serve and what the cost may be if you are paying OOP. Figure out a few places where you and your party might like to eat and go from there. Don't let booking ADR's become a chore or hassle, it's one of my favorite parts of going to WDW.
