As others have mentioned, it really depends.
In you're talking about the core of a system or a recurring mechanic, I prefer a number. Rolling more and more dice, especially if the quantity varies, is not very fun for me. I prefer to have a solid bonus and feel like it's harder to fail on that roll. I think an extreme example of this would be systems like the Warhammer 40k game where people roll a handful of D6s and then have different treshold for wounds and stuff. I would have something like that.
However, an occasional additional dice is great fun. When a bard gives me a die for a Bardic Inspiration if feels great because we tend to pass a physical die around the table and it really makes me feel like I have a resource I can use when I want and then I can clearly see how it has made my roll better.
And to go against my own argument, I also dislike games that have a ton of bonus that end up stacking or not. I've started playing Starfinder a few months ago and there's very little things I hate more than trying to remember if a bonus is categorized as an insight bonus, a circumstance bonus, a divine bonus, an enhancement bonus.
5e doesn't have enough crunch for me, but I'm still very appreciative of the advantage system because I feel it made room for other more interesting options instead of the never ending stacks of bonus.
