I have the impression that iTead and Seeed are using the same PCB manufacturer behind the scenes, so you can choose one or the other and will get the same quality.
From order to delivery you'll have to count about three weeks (1 week for production and up to two weeks for the shipment). My last order was sent on January 6, was shipped on the 13th, arrived at the border on the 19th, waited in customs for a week and was at my house on the 26th.
These services have made hand-made PCBs for me irrelevant. The quality is excellent and the price is low. If you need it faster you can pay for faster shipping.