A few comments on some of these projects: Keras is pretty much the best way to do almost anything these days. If you are starting out learning, use ConvNet JS, but after that switch to Keras. TFLearn is really nice if you are already using Scikit. There's lot of frameworks on there: TensorFlow, Caffe, CNTK (that's a lot of stars for something no one outside MS uses!) Theano, Torch etc. But I think the sleeper there i…
I ported ConvNet JS to C# in order to really understand what's going on: https://github.com/cbovar/ConvNetSharp
Top tip: If you use the matrix and vector classes in math.net then you can optionally configure it to use optimised version of e.g. matrix multiplication, that map through to one of the providers, such as Intel Math Kernel Lib, OpenBLAS, and I think there's a CUDA provider too.
I tried the Intel MKL one and the dense matrix multiplication was about 60x faster than a plain C# version.