Well I actually started with Meteor and looked for an alternative as well. I thought React would be the one but then saw backbone. I like it but it didn't feel the same and then I ran into Ember.
Ember uses handlebars which is a lot like Meteor's spacebars templating engine. As far as being a full scale framework I have not seen anything like it. But similarly you can build a back-end framework using Mongodb and Express on Nodejs and either build the ember app into the node server side or you could proxy the two on the same host.
In the end Meteor is pretty amazing and they have their hands full. I wanted to move away from the framework only because I am looking for a job in web development and I have only seen on job posting out of 1000s that had the word Meteor in it.