Granite is a natural stone, and there can be considerable variances regarding look and colours even within the same stone - so bear in mind that a small sample may not 100% accurately reflect the stone you eventually have (although a black colours are the most consistent).
Consider also that black (or very dark coloured) granite can be tough to keep looking clean and tends to show all the smears and watermarks (this is made worse if you have lots of natural light shining across it).
Many granites have large swirling patterns of different colours. These can be a problem where there are joints in the granite as the patterns do not match and make the join more obvious. There are some granites which are more consistent in their colour and pattern such as Kashmir white.
Corian is a man-made solid surface material. It is a type of acrylic which is non-porous and heat resistant up to 212 degrees Fahrenheit (not safe to put a hot pan on).
Corian comes in about a hundred different colours. Dark colours are to be avoided as Corian is not scratch resistant therefore dark colours show up scratches a lot more than the lighter shades. Heat and scratching are the two main disadvantages although any damage can be repaired. Scratches can be lightly sanded and polished out. Any mechanical or heat damage can also be repaired invisibly.
With Corian, joints in the worktops are invisible as the joining glues can be coloured to perfectly match the surface.
One of the major pluses of Corian is that you can have moulded up-stands (where the worktop meets the wall) which are great when cleaning and is very hygienic (and is used extensively in hospitals.)
Typically, Corian is more expensive than both granite and Quartz.
In our opinion marble is not really up to being used as a kitchen worktop and should be avoided.
It is quit soft and weak; it chips easily, it’s very porous and stains (so it needs to be sealed regularly). There are some Quartz products now are quite a good match for marble looks-wise but probably would not satisfy the real marble enthusiast.
However, we know from experience that some people will still choose marble even knowing all its negative points as it seems to be quite popular with some interior designers.
Hardwood kitchen worktops look great and are reasonably cheap compared to any of the above surfaces.
Their downfall is they need quite a lot of care to stay looking good. They can mark and dent quite easily (some more than others), and they are not very good with water and heat. You should avoid having hardwood worktops near a sink, hob or range cooker. We would advise that the best place to have wood is on an island or dropped setting area or peninsular - although they will still need looking after.
We always use wide stave hardwood worktops. They are more expensive than narrow stave and look fantastic. There are some pictures of these in our portfolio.
Quartz is a manmade product whereby quartz (derived from granite) is mixed with coloured resins and dies to produce an enormous choice of colours and patterns.
Quartz is stronger, lighter and more chip and scratch resistant than granite and some are antibacterial. It is also virtually impervious so does not stain like granite. Because the colours and patterns are consistent between all slabs, the joints in your worktops are far less noticeable than with granite.
Quartz is very strong and lends itself to being able to be prefabricated to create different looks. Another advantage is that you can select from a small sample knowing that the full slab will be the same (unlike with granite).
The only real disadvantage of quartz compared to granite is that quartz is more expensive.