7780: first BB, no data just talk plan, got me hooked
7290: wow, THE phone at the time! Recently bought one for $5 but thrill is gone ;)
8700: loved it at the time, great keyboard. At the time data plans were really expensive (rogers) so I kept getting them activated & deactivated based on my cashflow!
8100: Pearl; tried it once, hated suretype, tried it twice and loved it, lasted almost 2 years which is a record, loved the size
8800: tried it, hated it esp the squishy keyboard, gone
9700: had several, a classic "new style" BB but screen text microscopic in certain apps, done
9800: got one when first released, not crazy about it, gone
9100: Pearl 3G; great spare phone, still love the small footprint but not as crazy about suretype anymore, wife removed it from my possession, now in hers
9780: wanted "classic" style again but not impressed with lag, gone
9800: second go around with new warranty replacement a couple weeks ago, new philosophy about not trying to make it do the same things as an iPhone, so loving it
But to answer the question of my favorite, believe it or not I'd say either the Pearl 3G or the 9800.
Will probably take a pass on OS7 and wait for QNX.