In my opinion autos don't taste like onion, but everything else isn't up to standard of photos. When I was growing autos, my buds were kind of airy and didn't smell as strong as the weed I remember smoking. I thought it was my lights or nutrients. Then I switched to photo and my photoperiod plants are DENSE and reek like a mfker, not to mention the potency and the bag appeal as well.
I like autos but there are only a handful of breeders that can produce good results consistently like mephisto. I had two horrible autos harvests, one is Hindu Kush Auto from Master Sensei Genetics which was complete trash, maybe like 5% thc max. The other was Wicked Pissah Seeds' Auto Sour Sheriff, fairly decent strength, but took 120 days and half of my tent to produce only 2 oz of buds. I'm done with autos.
I grew mostly mephistos and if I ever have to grow autos again (hope not), I'll stick with them because their consistency and quality is the closest to photos, but even going from mephisto's autos to photo would still be a step up in quality. And to the guys that said you can't identify autos and photo buds, yes you can. I can at least. I can scroll through hundreds of bud pics on Instagram and I can tell almost always correctly before reading description which one is autos and which is photo buds. Auto buds are airier, less trichs most of the time, more pistils and more leaves, and tend to produce oddly shaped buds.