The HTC Dash has my vote as the "best buy smartphone", for a few reasons, but mostly because of the price. Amazon is selling this phone for $.01 with new T-Mobile 2-year contract and then you get a $100 rebate in the mail.
Switching from AT&T was a no-brainer, considering this phone would of cost me $300 with a 2-year contract extension and cost would have been around $80/month. With T-Mobile, I receive a comparable service for $65/month. Once again, the choice was very easy.
The only cons I've noticed are:
-that the camera could use an upgrade and maybe a flash.
-doesn't support SD memory cards
-a little slower that some other more expensive Smartphones.
HTC Dash tips:
1. Download Opera mini 4, this is a pretty cool browser for this phone and much better than IE. SEE DEMO
2. Download the HTC Streaming Media Player, so you can watch videos on YouTube mobile
3. Download GooSync to sync up with your gmail calendar events.
4. Sign up for a windows live account at Live.com, I do this mainly because it's easy to sync up my contacts from any Windows Mobile device.
If you have any tips, please leave a comment.