We tune many Autronics, Motecs, Vipecs and Haltechs mainly on the Jap cars. I like the Autronics and Vipecs only because I"m quite familiar with them but the other guys opt for the Motec, quite a range in prices of course.
With the Euro's you can do a lot more with the factory ECU's these days so unless your doing something unique its often worth sticking with the factory ECU.