Which method is best method to amplify 3.3 v output to 10 v to drive MOSFET Switches with Low RDs ? NPN transistor or DC-DC boost Converter?
Normal method would be a PNP with a resistor e.g. 100K between emmitor and base to hold it off, 

The base of the PNP is switched by an NPN transistor to ground (PNP base to NPN collector, NPN emmitor to ground and NPN base to micro via a resistance), 

In this case it would also be wise to give the mosfet gates a weak pull down to ground to keep them off (the PNP will leak a tiny amount, which would pull up the voltage otheriwse), e.g. 47K, 

Edit, missed the 42V, in this case you would fit a resistor in series with the PNP collector so that the divided voltage is about the 10V your after,