As I see it, it's a case of "horses for courses". The Scandi grind has the advantage of a chisel-like edge with it's inherant strength but some folks find them a little more difficult to sharpen properly than other edges. The way the blade thickens relatively steeply behind the edge can make deep cutting in wood difficult but the edge has a good degree of durability. Good hollow grinds usually have a thinner blade behind the edge and can be better for deeper cuts into firm material but the edge can lack the strength of a Scandi due to this thinner profile. A flat grind can be an excellent slicing blade, and depending on the angle of that grind and can be seen as a happy medium between a Scandi and a hollow grind, the grind angle determining how quickly the blade thickens behind the edge. Steeper angled flat grinds are obviously stronger overall, but can lack the easy penetration of thinner blades. Too thin and any advantage of strength over a hollow grind is lost. Covexed blades are becoming more popular as they can give very strong edges with plenty of steel behind the edge to support it without thickening too quickly. The covexed blade can be difficult for those with less experience to sharpen well, but a lesson and a little know-how soon cures this problem.
Which blade profile is "best" overall will always be a matter for discussion. Which is best for a particular application is an often argued matter too. Personally I tend to favour flat ground blades and hollow grinds for most jobs as I like the fineness of the edges I can achieve with them and they are what I am used to. I have a machete which whilst not having a full convex blade does have a well convexed edge and it does a great job of the chopping and general brush clearing tasks I use it for. Axes should, in my opinion, always have a convexed edge if sharpened correctly. My SAK I keep with its original flat grind with a well honed edge. Most of my locking folders are hollow grinds (I like Buck knives, especially the 110 ) and I have fixed blades in both hollow grind and flat grind.
I suppose there are those that would argue that as I strop all my edges to their final sharpness, I effectively put a small (tiny might be a better description) convex on all my edges, but this is such a small part of the blade that I think it's pretty irrelevant when it comes to the discussion of blade grinds.
As with so many things, it's probably a case of "suck it and see". Try various blade designs until you find the type that best suits what you want to do with it.