All these macro lenses are so good optically that it is a mistake to think that one will give you significatntly sharper images than the other. They are all so good that you will have to do some real pixel peeping to see any difference. None are bad, all are good, and it is just a slight difference on the degree of excellence. This is not like some other lens types where there can be visible differences in image quality between different lenses, in reality the differences between these lens are not so big.
Similarly don't fall into the easy trap of think that an extending type macro lens is always inferior to an IF design. Both have their advantages/disadvantages and the working distance advantage of IF designs only really starts past 1:2. You see when you are actually taking macro photographs, a shorter working distance can actually be an advantage at times and the length of the extension is an instant guide you can feel to check what distance the lens is focused on, without having to lift your head. In the macro distance - when everything is oof in the viewfinder, it is sometimes difficult to know where the lens is focused without lifting your head as both infinity and 1:1 can give an equally oof viewfinder look at intermediate close-focusing settings. It is easier with an extending type to sense where the lens is focused without looking.
I would make your decisions on which lens to buy, on the price, how they feel to you, weight, and if the lens is being used for things other than macro photography. By price, I don't mean the cheapest, just what you can afford or are willing to pay. If money is no object, base you choice on other factors, if you are on a tight budgest, then don't think that by buying a more expenisve one of these macro lenses, that it means your images will necessarily look any better.
I'm sure everyone will tell you their choice is the best, but that doesn't mean the others are bad, each one of these lenses has something going for it.
