There is no doubt that many developers will use wkhtmltopdf.
I think that the Pdfcrowd's selling points could be 1) wide availability - only HTTP is needed so it can be used theoretically on any platform 2) no need to install any 3rd party software which makes the applications more portable 3) API bindings
I think that the Pdfcrowd's selling points could be 1) wide availability - only HTTP is needed so it can be used theoretically on any platform 2) no need to install any 3rd party software which makes the applications more portable 3) API bindings