Personally, I use to recommend a generic map like Revo, APR etc for stage 1's, but these are just a flash and go, what it doesn't do is highlight issues with the car, as in pre checks, boost test leak etc.
I would go for someone reputable like Niki Gower at RTech. Pre checks are done on the car (so it's not all down to you to check over the engine), boost test leak can be done, and with custom tuners like this (although they will still be using a generic code to start with, and tweaking slightly), you can get the car RR at the same time, meaning faults, errors or if the car is down on power due to a boost leak can be spotted at the time.
All too many stories I have seen of cars being flashed on your driveway, then no way of checking if it is really performing as it should be.
Also RTech are VERY competitive on price, in fact they are probably cheaper than the likes of Revo or APR.
I have a custom STG3 map from Niki, and I would never use anyone else. A lot of my friends use RTech as well and he is the best in the business by far
Or there is Bill Brockbank at Badger5 who is also excellent, and can offer rolling road facilities and a stg1 map, with pre and after checks etc