I didn't see through the entire experience with them so I can only provide a small amount of info for you regarding my experience.
I decided to use BCIT ICES first for my ECA; however, they still hadn't gotten back to me a week after I first submitted my application to them (you have to wait for them to contact you before you can submit the fax for payment). I tried to call them during that week, and all the (very polite) customer service representative could tell me was that they were still in the process of reviewing applications and would contact me when they got to mine. They couldn't give me an ETA on when they might get to my application.
After a week, I got frustrated and submitted an application to WES, then sent an email to BCIT ICES to let them know I was cancelling my request, even though they had already received all of my documents and transcripts. Oddly enough, although they couldn't give me any update that entire week I tried contacting them, they responded within 5 minutes of that email to let me know they were about to start processing my application that day. I wasn't amused.
But, WES ultimately came through in the end (I got my results on July 21, and submitted my application to them on June 20; they got my transcripts from my university on June 21 or 22) so I'm not complaining.