Personally I played Tri before I got into Unite about half a year ago, and in Tri I'm (almost) always lancing. When I started with Unite I tried out every kind of weapon (as all types of weapons are available to you when you start out), but I emidiatly gravitated to the lance. It's naturally missing a few attacks (counter) as the game's older than Tri, but while still sometimes using other weapons the lance lasted me well into high-rank. Then, however, the lance isn't as good anymore, so I'd suggest mixing it up with other weapons as well.
I've not used bows that much myself (I've tried them out, but never quite understood the aiming of them (bowguns fit me much better)), however, I suggest looking into some hammer paths, as hammers are really OP in Unite. Everytime I've used a weapon (say lance, dual swords or gs) and it's not quite done the trick, the hammers have always been the safe bet to complete the quest. That and longswords.