It's a common problem for non-technical founders trying to hire their first engineer and has been written about quite extensively. One good resource that was on YC blog recently is this post [0] by TripleByte (it's basically marketing but also has good content).
Even if you're early stage, try not to think about it as a yes/no for the two candidates you have, but rather try build some kind of pool of potential candidates (even ones that seem very likely unsuitable). The questions you ask in each interview and the questions that other candidates ask you will be very helpful to get some kind of feel for what you're looking for, red flags, etc.
[0] https://blog.ycombinator.com/how-to-hire-your-first-engineer...