Second poll of the day, upvote what you want to vote for and feel free to reply to talk about it
4: Libraries and frameworks available
Libraries and frameworks specifically based around their stability, longevity, and level of support. The standard library plays a huge part in this as well.
Fantastic 1st party libraries > 3rd party libraries.
If devs are able to jump from project to project and the structure, constructs, operation, and style are largely the same as as foundation that facilities a high level of productivity. Stable 1st party frameworks also promote long term project stability and portability.
Not to start a holy war, this is simply a boring truth, .Net vs the JS ecosystem is a great example of contrasting framework & library stability and standardization.
3: Ease of learning
2: Community support
1: Performance
5: Other (specify in replies)