I'm actually testing the Liquid E right now.
It's fast, cheap and runs a fairly pure version of Android 2.1, so if you're looking for something more likely to get timely updates, it's what you want.
That said, the HTC Legend is definitely better built. Acer's phone feels... well, like an Acer phone: it's all about the specs inside to mask the fairly cheap build quality outside. The Liquid E won't fall apart in weeks, but the Legend is a unibody aluminum design just a hair's breadth away from a MacBook Pro in terms of rock-solid build. HTC's Sense UI is also quite nice, though it probably means you'll have to wait a few months for an official upgrade to a later Android version.
Weigh things along those lines and you'll probably have your decision quickly.