My first was the Samsung Omnia on Verizon. Could have been a decent phone if it wasn't for Verizon killing it... and the fact that it was WinMo 6.1 and not getting an upgrade. I now have an Eris and it is the phone I've been searching for.
First smartphone was a Sidekick 2008. I always thought Sidekicks were cool devices until I bought one for myself. I thought the phone was decent until I started using it for a while and realized it sucked. Sold that POS as soon as I could.
Like some others, my first was a Treo 600. I loathed that phone. What a gigantic piece of absolute crap. It completely turned me off of smartphones. I tried really hard to like that phone, but after a few months I ended up replacing it with a kick ass Motorola i355 super-indestructible-doubles-as-a-blunt-force-weapon dumb phone. Then eventually I gave smart phones another shot with a Motorola i920 with some form of Windows Mobile. Not a bad phone really.
God, Ive had so many. Most were Blackberry. I also was cleaning out and came across Blackberry 5790. Yes kids...no color screen. But back then, that was top of the line!! And it was Data Only!!!
My first smart phone was actually the Palm Pre. It was a good phone for a while until you realized how laggy WebOS is how the applications for it are extremely underpowered compared to most apps on Android Market and the App Store.