With the step up in size (an extra 3 inches/7cm), the Cordoba 15CM is my recommendation for a beginner’s concert-sized ukulele. There are many reviews commenting on the attractive appearance and warm, rich sound. Reviewers also like that it seems to stay in tune well. As for the other ukes, you can get the Cordoba bundled with a case, tuner, instructional DVD, and polishing cloth for $120 here.
A warning if you read the reviews on Amazon – there are reviews for the soprano Cordoba mixed in with those for the concert size. Unlike some listings on Amazon, there is (at the time of writing) no way to filter those out. However, the majority of the reviews are for the concert size, so you can feel confident that the average 4.7/5 stars is accurate.
Most reviews of the Cordoba 15CM are glowing (hence the large proportion of 5 star ratings), however interestingly, there are quite a few significant complaints about quality issues – poor finishing on the wood, buzzing, rattling, etc. One reviewer ordered two Cordoba 15CMs and received two very different instruments, down to weight and color. If you order the Cordoba 15CM, perhaps be prepared to return and exchange it on the small chance you receive one with quality issues.
Summary: Overall, the Cordoba 15CM Concert Ukulele is a great choice for a concert-sized beginner’s ukulele for those who are prepared to spend slightly more.