Yes, the Biotic build is weakened by the limit of armor, but once upgraded she will be able to have barrier activated 100% of the time, to offset that. Much the same way my Vangard had. In ME1 she will remain as such, because Sonoura is an evil sorceress anyway, and biotics is a sort of future spec for a mage. The biotics of ME1 are very powerful and only needs to contend with shields. In ME2 I might change her over to an engineer, because that class comes with a good selection of powers. Like AI Hak and the Combat Drone, which fits Sonoura as a summoning/charming character. Along with Dominate, as her bonus power.
Some people down play AI Hak and Dominate, as situational powers. I have sat and laughed myself into tears over using them both on enemies. But that was either playing as an Inftrat or using squadmates. Even on higher difficulties, once Maranda or whoever, strips one down to health. You can take out an entire platoon with the use of them both, and never fire a shot. All the while pissing my self with laughter. The sounds they make from turning one on the other keeps me in the floor.
As far as favorite weapon...I like them all for one reason or another. It would depend on the build, really. I guess for ME1, I would have to say the Sniper Rifle. Because I will choose it as a bonus weapon if I'm not playing as a Sldg or Inftr, so it is a 'must have' for me. Then I guess it would be the Assualt Rifle with Kinetic Coil and +X dam Orgn Rds/+X dam Synth Rds, pending on the enemy.
In ME2 my favorite weapon has to be the 'Locust SMG', without question. It is my main goto weapon with any build. But I use them all, pending. Now, my favorite HVY WEP is, above all, THE CANE!! That thing can take out almost any boss on any difficulty with one shot. The exception being, only a few on higher difficulty, like the Prath and Thras Maw.