Hello guys,need to know one thing,which is better for altitude hold,apm or naze controller?.I've seen some videos on youtube,naze looks better,but unlike apm it is not open source and does not support gps.So what is your opinion?.

APM is surely a better option.

Apm supports so many programs for many multirotors and ground vehicles  right?,what if i want to see the source code?,can i do that?

Yes. You can see and contribute for the source code, in the case of APM.

Well if you're not a beginner, I'd suggest to DIY it.

How could i see the source code?,and i really dont know how gyros work so i couldnt work on pid algorithm

PMed you!