A good place to start is looking up the specifications of your current Suntour fork: http://www.srsuntour-cycling.com/components/fork/XCM-27-5-5617.html
The important points are:
- Straight 1 1/8" diameter steerer tube
- Post type brake caliper mount for 160mm rotor
- 9mm quick-release wheel attachment
You will also need the axle to crown length to be the same or at least close. The Suntour page does not give it but you can measure it easily. I'm not particularly knowledgeable about MTBs but I am guessing that most 120mm travel forks for 27.5" wheels will have about the same length.