They are equally as drought tolerant but neither will appreciate a rocky clay soil and that will inhibit their ability to spread rapidly. Both would prefer a loose, well drained soil. And because of its low height and mat-like habit, woolly thyme will stand up much better to foot traffic than the much taller growing veronica.

Nothing kills my thyme, which has spread into the lawn at a rapid rate. If you plant it, you'll never ger rid of it. If you mow, you'll keep the flowers away, which will keep the stinging bugs away. There's nothing like being barefoot in a lawn with bees loving your thyme.

Gardengal, thanks for the info, perhaps I will amend the soil before plunking anything in it!

Sigrid, that's encouraging to hear. I think I will go with the woolly thyme.