spaCy's definitely the fastest NLP system you can easily use.
I'm told one of Google's internal systems is >10x faster, which is intriguing, and I guess unsurprising.
A research system was published this year that gets faster than spaCy by using the GPU. I think their code might be available, but I doubt it's production quality.
Here's the Lewis et al paper, which compares against spaCy and other systems for efficiency:
All of these papers are linked in the benchmarks section of the spaCy homepage: https://spacy.io
As for Keras being the most popular deep learning library for Python...I thought this was absolutely obvious? It was close in 2015, but now it's not. I guess if you count Keras users as Tensorflow users, Tensorflow might come out on top.