I always use Obeche, a medium hardwood. It can be obtained in thin planks from model shops or Ebay, and in large pieces from timber suppliers or the internet. It is yellowish in colour, cuts and carves easily and has hardly any knots. A beautiful wood to work. Most of my models are of iron or steel ships, so the texture doesn't matter, as it is all covered up with plating. Here is a lump of obeche on the first day of the Lord Ripon build (Steel four-masted barque).
Bob