If you're serious about handheld gaming, I'd recommend the 3DS XL as the best console on the market right now. Its double-sized screens, comfortable chassis, durable stylus and enhanced battery life make it a significantly more practical handheld than the vanilla 3DS - and its game library is sensational. Great games deserve great kit to play them on.
And it costs £130 from Tesco with a choice of flavours - or £133 if you want to spring for delivery. If you're more casual in your handheld gaming, though, consider the significantly cheaper 2DS with its many compromises and sacrifices absorbed by a tasty sub-£100 price. Thanks to Naralie @ HUKD!