I will admit that 3/4 did seem a bit much to me but wanted to see what others thought.
5/8 seemed like a good choice. As my initial thinking was I wanted to build something strong.
1/2 was my initial thought, but for the modest weight gain, 5/8 seemed OK.
1/4 and 3/8 just seemed a bit wimpy to me, granted I won't likely be putting anything that heavy on them.