Phenibut seems to have the most calming effect and provide a good night's sleep. Lately it has given me some withdrawl headaches but that was at larger doses.
While not as effective but still has a calming effect, I used 5-HTP with some success as of late.
GABA didn't do anything for me but I hear it recommended quite often.
Ashwagandha would be ranked below 5-HTP but still much better than GABA.
Anyone have experience with any of these or others?