REVO is excellent, both product and aftersales, but pricey.
If you want the hardware to switch beteeen std and REVO maps it works out over £700.
Im going Bluefin next time as I can get it for £450 all in, with AUDI forum discount.
Its a tough choice these days as there appear to be many smaller reputable companies competing with the established `bigger` tuners such as Superchips (Bluefin), REVO, APR, BBR, Oetinger, MTM, Custom Code etc...
Its worth bearing in mind that with Bluefin you can map you car DIY and there is a no quibble 7 day money back on the product, and its supported by Superchips who have been around for ever.
Good luck
Paul