It's better to get branded ones like Tektro, Juicy, Shimano, Avid, hayes, magura, etc, Avoid unbranded, Zoom and Clarkes. be careful that they're genuine. Any set coming from China for less than £40 is unlikely to be genuine. Search by those each of those brand names to filter out all the crap.
One thing to loo out for is the shape. On some, the gubbins on the levers runs close to the bars, and if you have other stuff on the bars, like a throttle, they don't fit. Have a look at what's on your bars and then look at the shape of the ones that you're thinking of buying, just to be sure.
These look OK
1 Set Hydraulic Disc Front and Rear Brake. The center position of the caliper can be automatically corrected through the adapter. Weight: Front wheel approx. 287 grams / Rear wheel approx. Hose Length: (Lefr)Front: 800mm /(Right) Rear: 1500mm.
www.ebay.co.uk
I must admit that I prefer the Shimano M766 integrated shifters/hydraulic brakes, that I fit on all my bikes. They're only 9 x 3 speeds. I always make sure that I have a spare pair in stock for my next build. Whenever I use a pair, I start trawling Ebay for the next one. I usually pay about £40 each. You can see enough room for the thumb throttle, right where you want it: