There is a bewildering array of choices of materials used to construct doors from . I will detail a number of them to help your selection process. I have also indicated their durability and characteristics. Links are to veneer colour samples to show wood natural colour characteristics.
Oak
The most popular hardwood choice by far for traditional and modern kitchens. There are many types and grades of oak depending on country of origin and how the oak is cut as planks from the trunk. This will effect the graining pattern and number of imperfections ie cats paws, shakes and colour variations. Good quality mass produced American white oak shaker style doors have quite a straight and plain grain pattern, with few knots and variation in colour. Lower quality doors have more variation of colour and imperfections, and do not look so good in a complete kitchen .Character oak style kitchen doors have various levels of imperfection and it is considered to add to a rustic look. With mass produced traditional kitchen doors you can sometimes see too much variation of colour, on cheaper doors, and too many sections of wood, and even though this will mellow, it is still not very good to look at to a furniture maker. Bespoke door options are bewildering, but important to clients when adding individuality. The finish to the wood can be un-varnished with wax finish, raised grain with light varnish, and wax finish. Smooth with heavy varnish layers etc. It is often up to a french-polisher to interprate the customers desires and provide a sample.
Oak sample link
Walnut
A popular kitchen choice and used more visibly recently. There are various colour variations from medium to dark chocolate, with a grain pattern similar to maple, and fairly smooth to touch. Generally used in a more modern context, but does make a beautiful bespoke traditional kitchen if mixed with painted wood etc.
Walnut sample link
Maple
One of my favourite woods for colour and pattern, but prone to turning yellow and mellowing badly. this can be limited by a white colour opaque laquer and does look better for much longer. Look at Marpatts Hepplewhite door as a good example.
Maple sample link
Ash
This is a wood I have used effectively and is quite lively for grain which you either love or hate like bovril. I like the light colour and it does mellow well.
Ash sample link
Chestnut
A pretty wood with lots of variation and interesting grain and colour. It can be difficult to predict when buying as a plank and sometimes can change from very light sand through to pink so be careful when looking at samples.
Chestnut sample link
Yew
Another very lively and unpredictable wood, with probably one of the most exciting grain patterns I have ever used, outside of burr walnut etc. I would say use it sparingly for contrasts, but if you are brave it will be a unique look.
Yew sample link
Cherry
Similar to maple in grain, but a much richer and pinkish red brown colour. Makes a beautiful kitchen but can be too much as a whole scheme is ,better used as high- lights and single pieces.
Cherry sample link
Applewood, Lime wood etc
These fruit woods are interesting and beautiful, but difficult to buy on the plank and unpredictable in quantities, to make a kitchen. They can look good in modern kitchens and traditional contexts, for ready made doors and are still used sparingly, so are good if you want something different.
Apple wood sample link . Lime wood sample link
Exotic veneers
Zebrano, Wenge, Macassar etc. Exciting to use for doors and worktops with very strong grain and colour striping. Used for contrasts mainly in high gloss kitchen layouts.
Zebrano sample link . Wenge sample link . Silver greywood link . Ebony Macassar link
Poplar or Tulip
Used extensively in Bespoke kitchen manufacture, with mdf centre panels because of its even straight grain and smooth finish for handpainted kitchens. Greenish in colour and not pretty to look at in the raw state, like tanalised wood. Is not very hard and prone to denting, but better than pine etc. Maple is harder and is used sometimes for hand-painting, but is very expensive to hide !
Used extensively in the kitchen manufacturing industry, and has various types and qualities. It makes a good carcase with melamine covering in 18mm. It is good for painted doors when high density and waterproof quality. It is good for side panels and large flat areas when painted or sprayed with colour. It can be machined and cut like solid wood , but again I stress that quality is everything, and it can furr when profiled and routed, so will look unconvincing on bespoke kitchens when not sanded and finished properly before painting.
Laquered mdf
Used for modern and traditional kitchens in a flat matt finish. Used for modern kitchens in high gloss finish. Again the finishing and sanding is crucial to get the best finish, and is often the differance between quality and rubbish. Painting quality for gloss finished doors is also an area to look at, because I have seen few sprayers who can provide a good blemish free finish.
Bespoke hand painted mdf
It is possible to produce a complete bespoke in-frame kitchen totally from mdf and it perform better than tulip and mdf mix. But here is the dilema ,most builders use cheap mdf and expect it to take hinge plates and perform like wood. It does not, so quality of mdf and good finishing are essential aswell as waterproofing.