Actually both will do the job. I would suggest you to use interfaces though if you just do type-checking as it is specifically designed for that purpose.
Classes and interfaces are powerful structures that facilitate not just object-oriented programming but also type-checking in TypeScript. A class is a blueprint from which we can create objects that share the same configuration - properties and methods. An interface is a group of related properties and methods that describe an object, but neither provides implementation nor initialisation for them.
From: https://toddmotto.com/classes-vs-interfaces-in-typescript
