TAD OP1 is the most versatile I've used for organizing small items
T-rings are good if you often clip things onto your webbing loops. A carabiner will pull down on the middle section of the loop and is bad for the stitching but the T-ring will distribute the weight better.
I need a water bottle holder that mounts to 3 loops high 2 loop wide molle and fits a nalgene but I haven't found one that I don't hate yet
