I use them both. Picworkflow is a great tool for keywording and so on. I never tried its retouching services, though. However, uploading to the micro sites doesn't really work for me. Often, some bug seemed to cut out part of the metadata for a number of images in a batch, which creates a time consuming mess when submitting to a dozen or so sites.
So I export/download metadata from Picworkflow as .csv, use EXIFTool for importing metadata into my Lightroom catalog and then upload to lightburner. From there I distribute to the micros, which most times works flawless and is free to use.

Hope that helps.