I know this sounds like a lame answer, and isn't exactly what you're asking for...

...but amazon is the best shopping experience for me.

Each item has a boatload of opinions.

Each item has items other people bought instead. What people actually bought is sometimes stronger than an opinion.

Each item has related items.

You can search for something, then sort by review score.

Ok, so it's not trusted friends, but I've found that trusted friends usually don't have strong enough opinions about just what I want. Meaning the car that my most trusted friend would buy isn't the car I would buy by a longshot. Different people optimize for different things.