I had the Palm pre on sprint for about 6 months before moving to the Droid and Verizon. The last version of the Pre I used was the last released version before 1.4 (1.3.5 I believe? It's been a month since I got my Droid).
Obviously I am biased because I am here, but I wouldn't go back to my Pre. In my opinion, the Pre has more artistic and operating system polish. It is fun to use and the apps for it use flicking motions a lot more than on the droid (I miss being able to go to the next or previous track in music by just flicking the screen). Notifications while the system is locked is better on the Pre as well, as you don't have to unlock your screen to get a quick summary of the contents of the text messages/emails/whatever. On the Droid, all you get is the icon and you have to actually unlock the system and pull down the notification bar to see a summary.
However, what the Pre has in usability polish it lacks in bug polish and some odd design decisions. While using the Pre as your primary phone the multitasking method of the card view seems so fun and it seems like it works great, but once you start using Android you realize how gimmicky and a pain it really is. Android manages all of that for you, and allows you to multitask to your hearts content without ever seeing an "out of memory" error as the operating system will automatically close background tasks for you only if the memory is needed.
Google maps on the Droid is LEAGUES ahead of the version on the Pre. It's faster to load, has street view, more layers than the Pre's version, and most of all has an extremely awesome turn by turn navigation that is better than most stand alone GPS units I have used, let alone the default one that comes on the Pre (at least on Sprint's Pre, don't know what VZ Pre's use).
If you use google services a lot, you will get a ton of benefit from the Droid because Google has managed to integrate everything into the phone in a very good fashion, from google voice to maps to google goggles, to google calendar. Everything is easy and simple if you use google services a lot.
Everything is also faster on my Droid than my Pre. Between web browsing, scrolling speed, and games.
Home screens on the Droid are amazingly useful as well, especially if you use some good widgets.
As to battery life, I can't really comment cause I used Seidio's extended battery with my pre and I don't use it for my Droid. That being said I can end an 8 hour workday listening to music with approx. 80% of my battery left, 60% if listening to Pandora throughout the day. I have never felt the need to not use my phone to conserve battery life, but that's just with my usage.
If you are an enterprise user, the exchange integration (from what I have heard) isn't the best. Your personal email and corporate email are separated into separate applications, as are your calendars. Droid does not have a lot of mandatory exchange remote policies as well (such as force lock, remote wipe, etc...) so if you require your phone to connect to your company's web server and they are strict, they might not allow you to use the droid with their server.
Finally, there are tons of awesome games and apps on the Droid. I can't really comment about the Pre's list as when I left the pre had a pretty lack-luster set of not just games, but general applications.
Everyone likes different things, so it's hard to tell. I can definitely tell you that I do not regret getting my Droid and selling my Pre.