AMD 100% is the best choice right now if you exclude the shortages. If you can get your hands on 580s for less then $300 or even $400 they're worth buying. They use the same amount of energy as a 1070 (give or take), and you can mine mainstream coins with them to get decent revenue.
While $300 is indeed a good price for 480/580 8gb cards, I see no point buying them for $400. That's a GTX 1070 price, and I think it's just a better card overall. Better in gaming, and better in most mining algos. I mostly have 1060s and 1080s in my nvidia rigs, but just yesterday added a 1070 to one of them. Without much tinkering, it's mining ETH at 31 MH/s (+700 MHz Micron memory) @ ~110W, so pretty much on par with Polaris. It's a lot faster on Equihash though (~450 sol vs 300 sol). Slower in cryptonight (no one is mining it with GPUs now, but still it's a mainstream algo so should be mentioned). And while there are of course niche algorithms that run faster on amd cards, for the past year or so nvidia did have more of those. Lbry, Lyra, Skein, Neoscrypt - those are just what came to mind instantly. I can't recall anything like those for AMDs at the moment (they most likely exist, I just don't know or don't remember any).
I'm not a fan of anything and don't care about brands at all, but when presented with a choice between amd 580 or nvidia 1070 for the same price I'd definitely get the nvidia. Simply because it's a more powerful gpu overall.
It doesn't matter what's a 'better card' as far as pricing or how they're marketed. A 1070 is actually worse then a 580 for mining. Look at how much you're making with Equihash, then look at how much you're making with Eth+Sia. Eth+SIA/DCR/PASC are much much more stable then equihash is due to market size, volume, and difficulty. A 580 is not only worth more then $400, it's a better deal even at that price then a 1070 as a 1070 can't compete anywhere. A 1070 is a inferior card unless you find a niche coin to mine (which AMD also has). Niche coins don't even factor into a comparison as they're easily saturated, the markets tend to crash, and they generally they don't last long.
If you're worth your salt as a miner you should be dual mining (which you aren't doing). You'll notice that you're making quite a bit less with a 1070 compared to a 580 due to the assembly changes Claymore added, which aren't present for Nvidia and no one is making (IE a better dual miner I mentioned before).
A 1070 is ONLY a more powerful GPU when you consider how they're presented originally and the markets they fulfill outside of mining.
AMD 100% is the best choice right now if you exclude the shortages. If you can get your hands on 580s for less then $300 or even $400 they're worth buying. They use the same amount of energy as a 1070 (give or take), and you can mine mainstream coins with them to get decent revenue. With Nvidia you have to mine niche coins which are easily saturated or you make like 30% less with a 1070 vs a 580 (Equihash vs Eth+Sia). AMD also has niche coins, which you can also find that Nvidia is bad at.
Mainstream coins offer stability and safeguards against your revenue dropping out from under you, either due to a big miner hoping on it, buy support disappearing, or the market just outright crashing. There is absolutely no reason to buy Nvidia. You offer absolutely no points to back up your argument besides 'Nvidia best4evar'. I mean I want to feel good about the $10k worth of hardware I bought too, but that's not the way reality works.
current generation of polaris cards (rx470, rx480, rx570, rx580) has this tlb trashing bug again with epoch from current and higher loosing half of hashrate on epoch 199.
It is observed with claymore miner with current drivers. Dunno if it can be fixed. So if nothing will change you will be sticked to low epoch dagger-hashimoto coins just like with Tahiti cards.
I'm almost 100% sure this is fixed with GCN 2 and higher cards. I have not seen this with Claymore miner on my AMD rigs, they're still mining at pretty much exactly what they were when they first came out. If you're getting subpar hashrate either your memory speed is lower, you have bad type of memory, or you haven't tweaked your latency properly. Hawaii is GCN 3, Polaris is GCN 4.
If it isn't fixed, do you have a source besides 'you can see it with claymore now' which isn't observable?