In my opinion, the concert ukulele is the best all-round size of ukulele. It retains the distinctive sound of the soprano ukulele (which tenor ukuleles don't always) while giving you an extra bit of room on the fretboard.
If you're thinking of getting a concert ukulele as your first uke, I'd recommend the Kala KA-C. Particularly if you're able to spend a bit more than the minimum.
The Music Farm do a quick demonstration of the Kala KA-C.
On eBay US
On eBay UK
Construction: Mahogany (laminated) top, back and sides.
Tuners: Sealed, geared.