What is the functional difference between using Alpha GPC versus CDP Choline when trying to prevent the dreaded racetam headache?

I know they both boost acetylcholine levels, but the price difference is pretty noticeable. I have read that CDP Choline has some uridine benefits for dopamine receptor repair, but Alpha GPC supposedly crosses the blood-brain barrier faster. For those of you running daily stacks for memory retention, have you noticed if one actually causes less brain fog in the long run, or are they basically interchangeable for preventing depletion?