Try the Ukulele Underground forum

http://www.ukuleleunderground.com/forum/forum.php

Lots of good advice there. You'll need to join if you want to post but it's free. There are so many well rated brands that it's difficult to list.

Alternatively find a decent local music shop that has a decent stock of ukes of different makes and try some out and buy what sounds best to you. That's mostly what I've done

I rate the Flea/Fluke range. Plastic bowl uke of distinctive design. They don't sound too wonderful on paper but the design and construction means they come with spot on intonation and set up out of the box and have good tone. My Flea is the one I play the most.

You can see the Flea and Fluke range here

You can get them in the UK at Southern Ukulele store and at Duke of Uke in London

Ukulele Underground is an excellent forum anyway friendly and supportive.