Whether you are looking for a shiro utsuri, hi utsuri, or ki utsuri, you look for the same thing. If you plan on showing the fish some day, you should choose a shiro utsuri because they almost always do better in shows.
It is very important to start by looking for a good head. The head of a shiro utsuri should have both colors (black and white) on the head. Do not buy a shiro utsuri with an all black or an all white head. Look for an interesting pattern of black on the head with about 40% black and 60% white. A lightening pattern of black down the face or a black V across the top of the head are favored, but any interesting pattern will do.
A body that is 50% black and 50% white is classical, but a higher amount of white is preferred in current judging. Do not buy an utsuri that is too black. The pattern should be interesting and balanced. All the black should be in large patches and the patches should all extend down to the bottom of the fish. Do not buy a shiro utsuri with a lot of small black spots. Also, look for good quality white. The hard part about all the above things to look for is that in a young shiro utsuri, much of the black is deep and not finished and the white may still be grayish or yellow.
The pectoral fins of a young shiro utsuri should be all black or have a large patch of black at the base. Avoid shiro utsuris with all white pectoral fins or with just tiny patches of black at the base. Make sure both pectorals match. Many utsuris may have one black fin and one white fin. Do not buy these.
Make sure the utsuri only has two colors. Especially on shiro utsuri, there should be no red spots.
After you have the right head, pattern and fins, make sure you have a fish with a good broad body and large fins. This assures you of good growth in the future. Also check the fish in a tub to make sure there are no defects or disease present.
In selecting a hi utsuri or ki utsuri, the rules are the same. All the comments about white are the same for the red of the hi utsuri or the yellow of the ki utsuri. For these last two, good quality is harder to find than for the shiro utsuri because the shiro utsuri is more popular and more are bred in Japan.