If are looking for a great value hydraulic disc brake setup then the Shimano Altus BR-MT200 Disc Brakes are definitely worth a look. These bring many of the features of more expensive and higher tier Shimano model brakes down to an incredible price. Great for trail or touring use.
 
Features:
Brake Lever BL-MT200 Right Front / Left Rear
Dual Piston
Hose SM-BH59
Hose Length1000mm Front / 1700mm Rear
Post Mount
Mineral Oil
Pads B01S Resin - Pads Mount with Split Pin
Rotors Not Included
Specs:
Lever:
3-finger Lever Length
22.2mm clamp 
Steel Brake Lever  
Aluminium Lever Body

Calliper:
Brake hose SM-BH59-JK-SS
Post Mount
SHIMANO Mineral Oil
B01S resin pads included
Dual Piston

In The Box:
1 x Shimano BR-MT200 disc brake, front or rear
1 x Shimano SM-BH59-JK-SS brake hose 1000 mm (front) or 1700 mm (rear)
1 pair of Shimano B01S brake pads
1 x insert pin
1 x olive
2 x caliper bolts
rotors not included and adaptors not included