Okay, back to the OPs question.
Picture an elegantly constructed, carefully balanced house of cards. Each card rests on other cards, and each supports other cards. That isn't Shadowrun.
Now picture a Jenga tower made by about two dozen people not working together. Some of them worked on it at different times, some of them actively tried to sabotage what the others were doing, occasionally a few people tried to remake the entire thing bit-by-bit, but at no point did anyone have a master plan or have any clue what anyone else was building. This is Shadowrun.
If you want a balanced game, you aren't going to get it here. The best you can shoot for is to watch out for some of the more broken things that you can avoid just by spot-banning them without having to rebalance entire subsystems.
Things you should just ban:
-Cyberhands and Cyberfeet with Armor Enhancement
1 essence for 12 armor? YES PLEASE.
-Emotitoys and Empathy Software
Trivial amounts of money for +5 to all my social skills? YES PLZ. It basically adds +5 to everyone's social skills at the start, and +6 a bit later when people can get response 6 without Restricted Gear. It also has the hilarious side effect of making technomancers really good faces as a side effect of doing what they wanted to do anyways and spending all of 6 points.
-Multiple Grenades rules from WAR!
Did you know you can blow up a main battle tank by taping 15 frag grenades together?
-Iron Will (Attitude)
Could work any of three or four different ways, all of them broken.
Things you need to change:
The Channeling metamagic causes the mage to use their own mental and special ability scores when using their own skills and powers. The spirit may still use its mental and special ability scores when commanded to act by expending services.
Other than that, Possession mages aren't actually better than Materialization mages, just different and good at different things. Two often-forgotten rules: you can't exceed augmented ability score maximums with Possession, and being possessed is visible and obvious.
Technomancer riggers are really good, just don't jump in and don't use autonomous drones. Use Command (which you can easily jack through the roof), and Machine Sprites (remember that they use their own stats even when in a node that doesn't support them, ie, they get to use their own Response when piloting). There is a bit of oddity here which is that the rules don't actually clearly state how sprites piloting vehicles is meant to work other than explaining that they work like agents except where otherwise noted. The way it is clearly meant to work is that they work like a Pilot program.