Main difference with the colors, is how early they bloom. The earliest bloomer is the white, the next is the lavender, followed by pink, and then red. Color choice, would then be based on what colors you prefer to have, and/or when you prefer them to bloom.

You will find there are two basic varieties of crepe myrtle, with the one being found in TX nurseries being a more vertical habit, with the ends of the branches more upright, with bloom.

A more common type in other parts of the south, is more of a horiz growth habit, with the blooms on the end of slightly drooping branches. These can actually look very "bushy" when well developed, and in full bloom, making them look less familiar to us here, in TX. These are quite common in Atlanta and other SE places.

Texas A&M's site has a lot of photos of crepe myrtle varieties.

Here is a link that might be useful: TAMU Crepe Myrtle Page

You can also check out this poster from the USNA. They develop quite a few of the varieties that you find around here. They've got a really informative website. Also do a search on Carl Whitcomb. Neither are the originators of the two varieties that you asked about, but there is good info none the less.

Here is a link that might be useful: USNA Crape Myrtles

there are dwarf varieties, even without pruning, stay fairly short, like 6-8' tall, and the trunks stay fairly thin.

then there are the regular ones, i've seen some over 20' tall when not pruned yearly. the past couple years i've topped them off at about 5-6' but this winter i let them go, and they're currently about 12' tall. the trunks are starting to get thick, about 4-5" wide.

If you haven't seen this info then this may help some.
Victor is a deep dark red dwarf 4-6 feet in height also in my experience as a nurseryman is a little prone to powder mildew. Locate in morning sun or all day sun to keep the mildew down.

Centennial is a semi-dwarf 8-12 feet in height fairly upright. mildew resistance is consider good. This gives a little more flexibility on planting in area with less morning sun. Hope this is of some use.
Happy Planting David