1st  Position NedPlay
2nd Position 32 Red Casino
3rd  Position Dash Casino
4rth Position Lucky Nugget
worst paying gowild casino (lost only with it)
this are the percentages had  in a full month
there's a strange new entry Piggs casino
first rounds pays as a crazy after a couple of rounds takes back all
maximum play time from 10 minutes to a quarter per casino is my advice
10 max 15 spins are enough to test the slot .
If it has to pay , it does from the start
cashed in a month from that casinos more then deposited (350%)
with 5 single deposits of 100 euros each
another trick
make small deposits of 20 25 euros max to check the money spent with more attention otherwise the gaming will let you forget the budget and pass the line
and when the money hopefully won becomes 100 200
immediately widthdraw it and look at the end of playing how much you have
spent and how much you have cashed .
prefer days from friday to sunday late to play seems that money can be win more easily during that time
 

Great advice croalx!!!!  Thanks A LOT!!!