I can see in whattomine.com, there showing 110% profit in 7 days.
what machine will be better for EthereumClassic(ETC) ?
The 110% just means that in a particular period it was 10% more profitable to mine than the preceding period compared to ETHEREUM. So its 10% more profitable but the profitability is still pretty bad.
Take a RX 470 4GB for example, it hashes at like 28MH/s using 130 Watts and makes $0.24 per day before electric, the 10% extra is only an extra $0.024. And if you got power higher than $0.08/kwh you are pretty much not making anything.
The ETH profitability will be 30% or so more profitable on January 1st when they delay the ice age and we get 13 second block times again.
today the "old grapic card" like Rx 470, Rx480 verycheap but the problem is 80% of them is 2nd hand from miner and i can't say the ROI will come before the machine dead