Differentiating between 32-QAM and 32-PSK
If we exclude circuit complexity (QAM would be more complex), in terms of a less required eb/No at the receiver, a 32QAM will always be better than a 32PSK. Take into account that in a QAM modulation, samples will have a bigger separation in the constellation, which means that more noise is required to produce a sample error.
Other option could be a 32APSK