I originally was tempted by Revo because their headline figures were more impressive than Superchips but there are now two strong reasons why I would go for Superchips.
Firstly some people I have spoken to who have Revo have not been getting the figures Revo quoted. In reality I sometimes run my car on 95 octane (oooh shoot me I know) and mostly on 97 octane. Revo's headline figures are quoted on 99 octane I believe. I suppose if you run your car on 99 octane all the time it would match up but I don't always pass a Tesco Petrol station.
Secondly I don't like the news that Revo don't supply your original map but instead their version of stock. I think the Superchips, in offering your original map on the handset, retains a greater degree of security and flexibility come inspection (whether by garage for a service, insurance in case of event or even with the proposed new MOT emissions testing).
Also with the prices of each tuner and handset there's not much in it as far as I can remember.