Best ML package in python?

I am new to ML and have been primarily using Weka. I've heard Python can be used for ML and since I use python for all my pre-processing, data mining and getting it into an .arff file I thought I would explore it.

Looking on Google I see a number of packages

• Orange
• PyBrain
• scikit-learn
• mlpy
• PyML
• others?

Which is the "best" to use? I guess that can be vague... which are the most developed, the fastest, offer the most features? A lot of my work is classification using SVM, NaiveBayes, J48, kNN, and sometimes NeuralNetworks.

Thanks