As someone who has done both WES and IQAS (IQAS was for my spouse), I would say, if you value your sanity, please go with IQAS. They do it in 15 working days and are contactable and more customer friendly. They stick to timelines. You do not have an online account like WES but they say right at the start that it will come in 15 working days (used to be 10 but they increased it recently) and they stick to that commitment. On the 15th day or even a day before, they will mail you a confirmation with the soft copy!
WES drove me up the wall. 40 minutes waiting time to talk to someone. Unanswered emails. And worst of all, its all very vague. They say 20 working days but thats from the time "evaluation in progress" starts. The whole WES saga goes on for around 45 days!