Well just in my opinion, the Optimus is a better phone. I've been a long time Palm User and owned several Palm devices, both phones and PDAs. I had considered, when the Pre and the Pixi came out, upgrading to them, but I just really didn't like how they looked. Sure, some of the Pre's features are better, but I just can't say I like the way WebOS works.
Also on the topic: Glad I didn't buy this phone when I was thinking of

Had thought of buying it on Wednesday (before Thanksgiving) since I was going to be working and I knew it'd be dead, but decided it'd probably be better to wait until Black Friday. Seems like a good choice