^ about reliability, onkyo receivers have been generally good and have been running cooler since the XX09 series. IME, older models did run pretty hot but as long as they're well ventilated they don't present any issues.
as to whether you should pick an onkyo or a pioneer, do an audition and let your ears decide (personal preference will come into play here.) best if you could go to a shop that sells onkyo, pioneer, and polk audio so that you can audition the exact gear combo that you're considering. be sure to compare the features that you might use (i.e. room correction, listening modes, video upscaling, etc.)