Yes, the question has been asked, many, many times before, but it's all good
You asked a very subjective question. First off, what you build has a huge impact on which manufacturer you're going to go with. Aircraft, it would be either Hasegawa or Tamiya. Cars/Bikes and other vehicles, well, that's subjective again. People like Tamiya because of their quality of fit, but I personally hate car models without a full engine, so thumbs down for Tamiya from me.
Armor, again the field is varied. I personally do not like Tamiya as their range of subjects is not that great, and mostly it's very expensive. Dragon is great, and lately Trumpeter is getting up there. My last few armor kits were all from Trumpeter, and I can't wait to build them.