Where is an up to date miRNA database and what happened to miRBase? miRBase 21 was published June 26, 2014 and was still in its growth phase. Why is it not being updated anymore or the project declared officially dead? ENSEMBL also uses miRBase as a starting point (http://www.ensembl.org/info/genome/genebuild/ncrna.html).

What do people use now as a good reference for miRNAs especially for less well annotated/sequenced species?
If you are still interested, last year miRBase generated new updates. Currently, according to ftp site the last release is 22.1. So, it is not a dead project and for more specific information you should reference the miRBase blog.
In order to get the best set of miRNA annotations, you have to define your target species or even if exists some related annotated species and then, retrieve the current annotation along different miRNA databases, but most importantly you have to be really clear about the definition of miRNA families, because it is clearly different in miRBase and also in RFAM.