What are the pros and cons of Keras and TFLearn?
TFlearn is a modular and transparent deep learning library built on top of Tensorflow. It was designed to provide a higher-level API to TensorFlow in order to facilitate and speed-up experimentations, while remaining fully transparent and compatible with it. Even with TensorFlow, however, we face a choice of which “front-end” framework to use. Should we use straight TensorFlow, or TF Learn, or Keras, or the new TF-Slim library that Google released within TensorFlow.

Keras is a high-level neural networks API, written in Python and capable of running on top of TensorFlow, CNTK, or Theano. It was developed with a focus on enabling fast experimentation. Being able to go from idea to result with the least possible delay is key to doing good research.

Straight TensorFlow is really verbose while Keras and TfLearn both seem solid, but the TfLearn syntax seems a little cleaner. One drawback to Tflearn is the lack of easily integrated pre-trained models. 

Actually there are so many answers for your question here and here and I quote some of them here.

TensorFlow is currently the mainstream of deep learning framework, they are all the wrapper of TF. Whereas, Keras was released at the age of Theano, and therefore having a good support from Theano’s users. While TensorLayer and TFLearn are both released after TensorFlow. A good reason to choose Keras is that you could use TensorFlow backend without actually learning it. Plus Keras tends to wrap up the model deeply, so you don't necessarily need to consider the backend to be Theano or TF, which is a big advantage of Keras. 

It depend on what do you want to do, fast prototyping or something else?

Keras : Many people are using it, easy to find examples on github. Suitable for beginner. Capable of running on top of either TensorFlow or Theano. Tflearn : Why no one discuss it? It is also a famous library, transparent over TensorFlow. High running speed. TensorLayer: Just release (Sep 2016), transparent over TensorFlow. High running speed. Easy to extend, suitable for professional, its tutorial include all modularized implementation of Google TensorFlow Deep Learning tutorial. TF-Silm: Just release (Aug 2016) similar with Tflearn, but no RNN layer at the moment (Sep 2016).

The best deep learning framework is the one you know best.