both the truepower and smartpower models are good PSUs. but you can't ignore the power output because that is the major difference between the two series (aside from the fan configuration, and the modular cableing of the SP500)
the truepower models are a bit more powerful. if you compare same wattage models spec-for-spec the TP models have a higher +12v combined max load capacity than the SP models.
the truepower models also have tighter voltage regulation. the TP models regulate to within +/-3%, and the SP models regulate to within +/-5%
cheers :wave: