I added dual 200 AMP Copper bus outdoor panel to support garage and shed.  Existing interior home panel was upgraded to 200 Amp but the wire is max at 150 AMP tops so I changed the Main breaker to 150 Amp for safety measures.  The new panel was upgraded to allow more more 30 Amp slots for breakers as compare to the old 125AMP panel.  For the SHED I used GFI only breakers.  Very expensive at over $100 for each breaker but safety is priceless.  I used lower cost, 30 AMP breakers for the garage and have over 20 x 30 AMP outlets.   Copper Bus for longevity, fast tripping and easier to repair in event of warping and high temp issues.