is it the same for
rosemary
anise
chives
chamomile
tarragon
lavender
thyme?

I've been surfing the net for these answers with not so much luck...

With chives, the flavour of the flowers is just as strong (perhaps a tad stronger!) than the leaves.

With lavender - well, it's the flowers you eat, not the leaves, so it doesn't really matter! Make sure it's the true English lavender, Lavandula angustifolia, though - other varieties taste more like camphor than anything else.

Thyme - the flowers and the leaves taste about the same.

Tarragon - if it flowers, you've got the wrong kind, not the desired French Tarragon. The weedy Russian Tarragon will flower profusely, but it doesn't affect the taste of the leaves, which are comparatively bland. The flowers of the Winter Tarragon (Mexican Tarragon Mint) are just as tasty as its leaves and make an acceptable substitute for the Real Thing.

I can't comment on the flavour of chamomile flowers - but since it's the flowers you're after, you don't have much choice in the matter!

Back to Basil - since it flowers so profusely, I don't see how you can do much about it except just get out the hedging shears from time to time to encourage more leaf growth. Makes good mulch.

Meantime - remember that there are many herbs which produce edible flowers. A list (not necessarily comprehensive):

Acacia, angelica, alkanet, alexanders, almond, anise, anise hyssop, apple blossom, banana, basil, bergamot, borage, burdock, calendula, chamomile, chicory, chives and garlic chives, clove pinks, clover, coriander, cowslips, crucifix orchid, dandelion, day lily, elderflower, evening primrose, fennel, forget-me-not, fuschia, gardenia, garlic, ginger, hawthorn (may), heartsease, heliotrope, Japanese honeysuckle, jasmine (J. sambac), lady's smock, lawn daisy, lavender, lilac, lime blossom, loofah, lotus, lovage, marjoram, marshmallow, meadowsweet, milk thistle, mimosa, mints, mullein, musk mallow, mustard, nasturtium, orange blossom, onion, oregano, passionflower, peach blossom, primrose, primula, pumpkin, rose petals, rosella, rosemary, safflower, sage, scented geraniums leaves and flowers, Scots Thistle, snapdragon, St. John's wort, sunflower buds, salad rocket, soapwort, squash, sweet violet, sweet cicely, tansy, thyme, tulip, violet, viper's bugloss, wood betony, woodruff, yarrow, yucca, zucchini.