I prefer the common (sweet) basil over all the others. You could try the Greek basil for a stronger flavour. Purple basil tastes exactly like the common basil.

The variegated sage has the same flavour and uses as the common sage. I only know the fruit-salad sage, and it really does smell like fruit salad.

I use curly and Italian parsley. The Italian has a more robust flavour, so it's really a matter of personal preference.

For general purposes, the common thyme is the one to choose. The cultivars all have the overtones of it in them.

Golden oregano tastes just the same as the common oregano.

I prefer spearmint above all other mints for taste and versatility. The chocolate mint is derived from peppermint. Some people don't 'get' the chocolate flavour from it, but I do, strongly. I haven't tried the others you mention, but mints like basil mint do actually taste a bit like basil, with mint overtones. I don't think you'd notice much flavour-enhancement in fruit salads etc.

IMO, garlic is garlic!

I think Genovese basil makes the best pesto. It's really delicious. I don't find purple basil to have much flavor at all. Cinnamon basil has basil flavor with an aftertaste of cinnamon. I look good old regular sage for cooking. Bergartten has larger leaves, if that is important to you. The tricolor, purple and golden sages tastes like garden sage, but give color interest to the garden. The fruit sages are salvias, but not salvia officinalis (garden sage). I grown pineapple and honeydew as annuals here and they really do have the taste you would expect from their names. English or French thymes are good all-purpose thymes. Lavender thyme doesn't really taste of lavender. Lemon thyme definitely has a lemony taste and is terrific. Rose-petal thyme smells of rose-scented geraniums but looses much in the taste. Of the mints you mentioned, I grow spearmint (Kentucky Colonel) and chocolate mint. For the chocolate mint, it really depends on your individual plant. Mine has a definite peppermint patty smell, but not as much to the taste. Some others have chocolate mint and you would never guess the chocolate. Spearmint is delicious, but I like black stem peppermint even better. Crystal porcelain garlic (a hard neck variety) has large cloves per head. The largest cloves would be elephant garlic, but the garlickiness isn't as strong. You can also do a search for garlic varieties to find which ones have the biggest cloves. Best of luck with your garden and your future dishes!

I am not very tempted by the exotics. I like the traditional herbs the best. Though I did have a rose scented geranium plant which was pretty amazing. If I brushed by the leaves of the plant, later on I would find the scent of rose on my clothing. The slightest contact with the plant yielded an amazing amount of very pleasing frangrance. When I dried leaves from the plant, they retained the scent pretty well.

I like to use whole leaves of basil as a garnish. I learned that trick from eating in Thai restaurants. Last week I made a beef noodle soup. At table I served the soup with whole basil leaves on top, and lime wedges on the side. A spritz of fresh lime and the fresh basil jazzed the soup up a lot.

I used to have a recipe called 100 Year Potpourri. Unfortunately, I lost the recipe. I made up a batch about 35 years ago to give away as Christmas presents. I kept some for myself. It is still very fragrant. The trick to this recipe was that one should add a few drops of brandy to the potpourri every year to freshen it up. The recipe was heavy on spices, and iris root was used to keep the potpourri from molding. One can obtain powdered iris root from a pharmacist. It is often called orris root.

A friend of mine made headache pillows to give as gifts last Christmas. She used a satiny fabric. She filled the small rectangular shaped pillows with lavender and chammomile. Chammomile is a ragweed. A lot of folks with hayfever allergies wouldn't want to be laying a pillow fragrant with chammomile over their foreheads to soothe a headache! I had to stick mine in a heavy plastic Ziploc bag because I immediately began to sneeze as soon as I unwrapped my gift. I wish she had only used lavender to stuff her headache pillows.

Here is the recipe for the potpourri that i believe you are describing lorna-organic. It can last 50 years or more.

Half Century Potpourri

3/4 cup salt (non-iodized)
3 Bay leaves, crushed
1/4 cup allspice, crushed
1/4 cup cloves, crushed
1/4 cup brown sugar
1 Tablespoon Orrisroot powder
1 Quart partially dried Rose petals, preferably an old species
2 cups mixed, partially dried fragrant garden flowers (Jasmine, Lavender, Orange Blossoms, Violets, etc.)
1 cup dried Fragrant leaves (rose geranium, bee balm, lemon verbena, etc.)
2 Tablespoons Brandy

Mix together salt, bay, allspice, cloves, and sugar. Blend flower petals and leaves with Orrisroot powder. Place some of the flower petal mixture into a crock and sprinkle with some of the spice/sugar blend. Continue altering layers ending with the spice/sugar blend. Add Brandy, weight mixture down with plate and cap tightly. Stir every day for one month. Then you can pour it into small containers. Refreshen every 2 years with Brandy or whenever the mixture dries out.

Just one point - I have found the tricolor, Icterina and purpurescens sages less hardy than the plain. These are cultivars of Salvia officinalis which is the one you want for cooking. Many Salvias/sages, e.g pineapple sage, are not cultivars of S officinalis and are purely ornamental.