I love the use of butcher blocks in the kitchen. They are beautiful, highly functional and quite sanitary when treated properly.
The biggest downside is the maintenance. Which is why I like to see them used as a small section to the countertop or on an island.
A 2-3 foot section in the prep area is about perfect. It's large enough to chop and dice anything and it's small enough to easily maintain.
Traditionally, end grain butcher block has been the top choice for food industry professionals. Personally, it's my favorite look. But everyone has their own opinions; edge grain and face grain are also available.
Traditionally hard maple was the favored wood, because of it's tight grain and availability. Now more and more species of wood are available from all over the world. Brazilian cherry and mesquite are harder than maple.
If you want an exotic hardwood custom-made butcher block, you can get it, but it'll be costly. On the other hand, you can find stock butcher block at very reasonable prices.
Care and Maintenance
The longevity of your butcher block is dependant upon proper care. If you take care of it, your countertop will serve you for a very long time.
Follow all instructions provided by the manufacturer
Regularly (bi-weekly preferred) apply mineral oil to all surfaces
Wash with mild soap and warm water
Dry thoroughly with a cloth after washing
Lightly sand and apply mineral oil to nicks and gouges
Cut or drill without finishing all newly exposed surfaces immediately
Spill vinegar on a mineral oil finish (Causes cracking and warping)
Use harsh cleaning chemicals
Use an organic oil to refinish (organic oils such as vegetable and olive oils go rancid and promote bacterial growth)