Any of the alloys that end with the letter "O" are too soft. "O" means annealed, or softened. The common alloys are 2024-T3 and 6061-T6. 2024-T3 is what they used to call "dural" or "duraluminum". It is harder and more bend resistant than 6061-T6. It is also more expensive. Most of my experience is with racing and carrier planes, which are typically harder on landing gears than stunt or sport models.  I only use 2024. For two wheel LG, I use .090". For single wheel gear I use .125". If weight savings is your top priority, use 2024, and see if 1/16" is enough for your needs. If money saving is the goal, try.090" 6061. Whatever you try first, remember that if you can make one LG, you can make more!