I chose the oldest LTS (3.4) for some old hardware that prefers it, then the newest LTS (3.11) for good general long term stability, and the newest released kernel (3.13) for bleeding edge features and testing.
Please do continue to offer several kernel options for Manjaro, as I feel this is a key advantage of Manjaro. The reality of the Linux kernel is that there are frequent regressions that lead to hardware or functionality bugs. Forcing everyone to use the latest (but not always greatest) version of the kernel isn't good for everyone, whereas using a very old LTS kernel for everyone also isn't ideal. That's why I chose the two LTS kernels plus the newest kernel, which should keep everyone happy, and should still give users a refuge from kernel bugs that pop up in certain versions.
Thanks for all the work that goes into making Manjaro viable for many different users and scenarios!