I've tried in Daily tournaments but I only ended up in 103 I'm not sure what's the best rank to get rare cards for DT but I have read that you only have a one shot chance and I'm not too sure about elo but I want to know from you guys which game mode is the best ?
ELO Has a higher chance of a good reward. But they are only awarded once a week. Also you have to be good as only the top 100 players I believe are eligible. DT however if you place in the top 150 daily in both Extended and Standard has a very low chance of getting a CR and the better CRs are given to the one in 5 who have the higher DT standing so again you have to be good. There is no easy way to get them unless you are good at making money and buy them. And in that regard I would say Survivor is the fastest way.