You will probably get most recommendation for iPhone just because of the massive number of users. As Canadian, I love supporting anything that is made in Canada, so Blackberries are sweet. I thought long and hard between a BB, an Android device and Palm, and ended up getting Palm.
I am in love with my Palm Pre Plus. Once you play with it, it really is difficult to compare. Why? True multitasking (work in dozens of applications at the same time), physical QWERTY keyboard (it was the factor that kept me between BB and Palm), gorgeous design (it really turns heads and people asking me what kind of a phone that is when I go out), crystal clear reception (and yes, you can hold it ANY way you want to), charging wirelessly. The feature I found absolutely great was Synergy - it syncs information about a person from many sources (SIM card, Facebook, LinkedIn, Yahoo, etc) and organizes it in a single contact card, so you focus on the person and not on how to reach him.
webOS 2.0 is due to come out soon and it will also support Flash, better app management and working
The only negative is battery is weak that comes with it 1150, but I purchased a stronger one for $30 on eBay and it lasts me a day no problem.