1. St.Johns Wort - don't have much experience with it and haven't researched it, so I can't really comment, although it does have a lot of history behind it.
2. Kava Kava - much use with this herb. I rather enjoy it and find it very useful for stress, it's very calming. Look into a liquid tincture, pills standardized for kavalactones, or kavalactone paste - it's time consuming to prepare the traditional method and really doesn't taste good. The studies showing it to be harmful to the liver were from products that contain the stem, and not the root. Traditional use hasn't shown any liver problems to my knowledge.
2. Theanine - probably my second pick. Very safe, effective, noticeable - it would help with anxiety, but also has a very nice focusing effect, and pairs great with caffeine.
3. Bacopa - an awesome herb, but I think for your purposes there are better options.
3. Valerian - used more as a sleep aid isn't it?
4. Passionflower - tried a few times, does give a bit of a spacey feeling, can't comment on it's effectiveness for anxiety.
5. Kanna - had a sample so I've used it a few times. Effects serotonin levels right? It wasn't great in my opinion, I'd look for more GABAergic substances.
6. Lemon balm - I do recommend lemon balm - it's very mild, but taken continuously for some time might help.
7. Sam-E - I love SAM-e, lots of energy from it, good for so many things. Get some and give it a try, I was over my anxiety by the time I started using it so I can't comment how it affects that directly, but it's a known mood-booster.
My top picks would be a good kava extract, theanine and SAM-e. Don't try them all at once, start with whichever you prefer and give it a week or two. Stop use before trying a new one, and only after you've tried their effects independently would I suggest trying combinations.