I maintain two phone, US and Canada.
I originally had the BlackBerry Storm with Verizon, and a BlackBerry Curve with TELUS. Texting on the Storm was more painful than putting Bamboo sticks under your fingernails, so much so that I returned the Storm and got an 8830 World Edition on VZW... I then sold my TELUS Curve and got a Storm, only because I need a cool phone, and a work phone...
I use the Verizon (8830 WE, work phone) for emails more so then the Storm, so I sorta had the phones backwards.
Long story short, depends on what your looking for, but typing on the Storm is difficult. They told me to give it 2 weeks to settle it... I gave it a week and a half and discovered that it taking 30 minutes to write an email that used to take 2 minutes to write was riDONKoulous! AT&T (GSM) have a pretty cool new Curve out.