I think that slots are way better than dice because of their payout structure. Lets say you are hunting 99x in dice, in this hunt you will not get paid if you hit 98x. But in slots things are different and you will get paid for every hit though you are aiming for jackpot.
I know that most of the slots pay like 80-92% of what goes into slots but still if you compare it with dice (specially hit and run method) it is more profitable in long run (although in long run you will eventually loose in both games because of house edge)
I want you to ponder upon this and please tell me how much I am right in this line of reasoning.
If we approach this mathematically:
For double dice which is generally used the winning percentage will be : 1/6*1/6= 1/36
In terms of slots the machine is quite different , all casinos use a different kind of slot machine, at some slot machines they might use 10 changing images which have different payout.
The percentage is quite lower as compared to the dice one .
When we are talking about the payout too , in terms of slots it's really really rare that a person hits the jackpot but I have seen some winning in dice. Payout in slots is better but at the same time it so quite rare.
Overall as for me dice has a better chance.