Here's what I like about my Evo the most, I guess: The Big Screen.
I read a lot of eBooks - love Project Gutenberg, am constantly downloading and reading. When I lay my Evo down on top of one of my all-time, most re-read paperbacks, the default Georgia font when reading eBooks from that site is virtually identical in size - and much, much clearer on the Evo. Easy on the eyes is an understatement.
I use Google Gesture Search (free, Market) a LOT because I have hundreds of contacts in my phone. A larger screen lets me rush or get sloppy, yet still get the job done.
Video jukebox. I download favorite YouTube music videos and just store them for when I feel like that sort of thing. At that point, no worries about downloading, I'm good to go right away - the bigger screen makes the difference.
TV - I'm a huge Babylon 5 fan. If you have 2.2 on your Evo as many of us do, you can go to this site and watch full-screen episodes -
Babylon 5 Full Episodes from The WB - Watch Free Babylon 5 Online on SlashControl
Google Sky. Love Google Sky. Goes nicely with my son's 10" and 12" telescopes.
Newsreader - just like eBooks, some days I'm a news junkie.
Can all of these be done in a spectacular fashion on a Vibrant? Yes (with the proviso that 2.2 is still coming for that).
Are all of these things just a little better on a little bigger screen - don't kid yourself, you know they are - see for yourself.
And the kickstand. Not a gimmick. It grows on you. Put your favorite tube or vid on the Evo and prop it up next to you while you type a reply to this or the next. Now - put the Evo out of sight, and try that again with the Vibrant. Use any little desktop prop you think might be handy.
For me - Evo.