Id say 3DMark FireStrike that will give you a good overall idea of how your GPU is preforming and also if it is stable. Superposition is also pretty good and will stress your GPU pretty hard. FURMark is a good benchmark for overall raw performance but not so much for stability.
If your looking to test your GPU in practical scenarios though and not just looking to see how much performance you can squeeze out of your GPU I personally think it is better to test in actually game play rather than synthetic bench marks. Synthetics by design are going to stress your GPU much harder than really any game would in real life.