We can't direct a particular altcoin which results into profitable trade but still here are more chances to do some more work for bitcoin and altcoin trading .
Here in my opinion it is to be best to buy BLRY and PAK .
For both these two , I have a reason BLRY is that altcoin in the list of altcoin which is more fluctuating , it means BLRY can give huge profit speedly And Secondly PAK is not much famouse , it has very big difference between its buy order and sell order , So through making order of buy and then sell you can make better profit , I am doing the same with pak and made about 0.009btc in one month with 0.02btc .
here you should have option of PXL coin , conditions for this coin is also same .