Targa are a well known German company, and their computers are usually available from Lidl. Acer are also a very well known company, and their products are available from many outlets including superstores.
Acer seem to have a mixed opinion about customer aftercare service, some people have had problems other people have not. Targa doesn't seem to get much publicity regarding aftercare service, perhaps due to scarcity on the UK market, and perhaps good aftercare!.
There are stacks of systems on the market, perhaps if you tell us your requirements, then someone may have the solution and the price suitable for you.