These 2 sites have been here for years doing their promotion through signature campaigns. Also, 777coin does a daily give away of 0.00001000 BTC in the games and rounds section, if posted in a following format. But we have many other gambling sites now due to people coming on the online platform in this work from home time. Some of them would have captured a certain % of market as well.
Bitvest and 777coin are old gambling sites. I am sure to use more and more after they continue to run signature campaigns without pauses and now they keep rolling, but in terms of appearance I am less attractive, what I am comfortable with in gambling sites is Fortunejack with a good interface and they continue to upgrade every time and even their promotions are quite good too in the last few weeks.
I love Fortunejack