I bought on Igogo.es couple of times. My last purchase was Vernee Thor (order IS*******166012).
The most important thing of this seller are the prices. In most cases they have lower prices then other sellers.
Second thing is fast delivery. They sent packages within 48 hours after making an order.
Customer service is also very fast. They answer within 24 hour.
Last but not least, they offer good customer loyalty program. For purchases you get IG Points and next purchase could be cheaper if you use this points.