Hi,
If you read all the 'horror stories' in the internet about certain laptops and brands etc, you'll never buy anything!
I've got an XPS15 I bought in late 2014, the highest spec available at the time and it's been 100% faultless. Other's have had issues. Some people have fantastic Apple Mac's and others who's units have plenty of problems and issues. A few good people I know are Apple service centre engineers and technicians and they're always busy fixing Apple products.
Depending on what you use the machine for, there's good machines in every price bracket and form factor. To reduce risk, as suggested buy from places like John Lewis, Costco where there's fantastic customer protection. If you are more confident in looking after your machine, then look at discounters like Ebuyer and other online retailers/specialist computer builders. PC World can be a good place to buy as well (aside from all the internet horror stories!)
Many will say it's important to get to know the feel of the laptop which is excellent advice. I personally don't need to go to that level as 99% of my usage is via a good bluetooth keyboard/mouse, however, when I am out and about with it, I do find the XPS great to use directly.
Good luck with everything once you buy!
Cheers, DtM ! West London & Slough UK!