Where there are plenty of choices, I'll lean towards the "Fall" varieties. Hopefully you do have 30-50 days between scorching-hot-summer-drought and fall frosts. If not, you'll have plenty of tender salad come first frost.
These Asian greens have so many names that seem designed to tempt Western gardeners (or at least be familiar):
"Spinach Mustard"
"Chinese Broccoli"
"Chinese Kale"
And they're all cool as little salad greens.
