Agree, the calculation is obviously different so it is hard to compare but if someone is a hardcore slot player, I can say that duelbits will give better bonuses (especially the level up bonus) because the amount of bonus is calculated from the house edge. If we gamble mostly original games, I think stake give better bonus so it is about preferences and about our passion on which games we mostly play. What I like on duelbits is that the level up bonus is divided into several steps on each level or it can be claimed every xx wagered amount while in most other casino we need to meet the wager requirement for each level which can take so long to achieve.
There are many things for consideration, not only better or worse bonuses. Because when we use a platform, we must to use a safe and secure one as well as trusted in payment and withdrawal processings for users.
Bonuses are like extra things, tipping on top of many things contribute to a platform infrastructure, but not the most important. Short term, bonuses can make us feel exciting but in long term, other factors have more important roles to bring high quality experience to users.
Duelbits with their history in gambling industry and in the forum, is a trusted company. I am unsure that their level up bonus program is the best or not, but it's not most important as said.
, even less if they are small gamblers. 
