OK I'll give this one a go.

As each carrier vary in their technology your decision will reside there first. For eg: GSM/CDMA/iDEN the most common North American network standards.

If require a phone first and email second the Blackberry 7100 series is an excellent device.

BB 7100:
http://www.t-mobile.com/products/ima...&class=pda

If your looking for a more traditional Blackberry which strength is email first and phone second. there are multiple offerings.

BB 7520:
http://nextelonline.nextel.com/NASAp...neDetailAction

BB 7250:
http://www.verizonwireless.com/b2c/s...edPhoneId=1588

BB 7750:
http://www.verizonwireless.com/b2c/s...edPhoneId=1558

BB 7290:
http://www.shoprogers.com/store/wire...mp;summar y=1

BB: 7780:
http://www.shoprogers.com/store/wire...mp;summar y=1

Offerings will vary from carrier to carrier, the links above will provide some insight to the current models and network technologies.