I tend to alternate between 1 lot of Tesco Momentum 99 (it's only 5p more than Tesco standard) and Shell V Power (10p more than Shell standard) But in the past I have always avoided supermarket fuel, but reading posts on here people say its fine, but it still feels alien to put Tesco in.
....Volkswagen recommend the higher octane fuels (such as V-Power and Momentum) for the 2.0T FSI engine - They state so on the fuel flap and also in the Handbook. Although the engine will run on 'lesser' fuels it's not doing it any favours and in my opinion is a false economy in the longer term. Also, if tuning, most remaps assume V-Power or similar.
Apparently Tesco 99 is made specially for them by an outside company, so might be decent, they even sponsor BTCC team MG who Jason Plato drives for.
....The concensus of opinion, including more scientific published tests, is that Momentum 99 is a good alternative to V-Power. Sponsorship is all about marketing and getting the financial support from anywhere and everywhere they can but we must assume that Plato's team cars actually do run on Momentum.
For historical family loyalty reasons I favour Shell and therefore V-Power and my car is tuned for it but I am happy to use Momentum 99 when industrial disputes get in the way of supply.