Oh my, aphids. There are more than one variety of those little buggers and different plants attract different aphids. Suggestion-keep your fertilizer regimen a bit low on nitrogen since lush and overly green leaves are a magnet for aphids. It's nice to see a bunch of nice green growth but the bugs like that too. Actually, the appearance of aphids is how I tell I've used too much N. Hope this helps.

I like Nasturtiums as a trap crop--it keeps the aphids occupied.

I did not apply fertilizer last year, which is when the aphids were bad. This year, I amended with some half-composted dead leaves, grass clippings and stuff. Too much N is most likely not a problem at all.

The Swamp Milkweed next to my tomatoes is covered in milkweed aphids, but those are the only aphids I've really seen around here. The usual red/green/tan species haven't been attacking the tomatoes or anything around them.

That's why I'm saying I think the basil and/or cilantro has helped to keep them off this year.

I like nausturtiums because they are a trap crop and the deer won't touch them. But unlike some trap crops, like radishes for flea beetles, aphids on nausturtiums act as a reliable food source for predatory insects like ladybugs, which then also attack the aphids on the tomatoes, keeping their numbers from exploding. I don't believe that any companion plant will drive off pests from near by plants, it just doesn't make sense that a 2 ft tall companion plant at the base of 6 ft tall tomato plant will scare off a nearly microscopic bug, nature just doesn't work that way for things trying to scratch out a living. If you had tall marigolds enveloping short lettuce it might be a different story.

Queen Anne's Lace (Wild carrot) is a wonderful companion plant in that it doesn't have to be next to the target plants, just in the area (and once established it grows striongly and self seeds the second year and after). It grows as soon as snow starts to melt and blooms early in the season to draw in ladybugs and hoverflies while the tomato plants are still little. Nausturtiums take forever to grow. but are large enough by the time the QAL dies back. As I said, my hungry deer won't touch either of them.

there is a book titled "Carrots Love Tomatoes" that might help. i personally use dichotomous earth to control most of my bugs. one year is put a tablespoon of it on each head of cabbage and i had zero cabbage worm and no white moths.
i put it in a garden sprayer to spray my garden. i spray every thing. i also spread it around on the soil around the plants with one of those cheese shakers they have in Italian cafe's.
about dichotomous earth. it is also call fossil flower. it is not harmful to humans, plants or pets. it is very fine textured like talc powder. it is very shap and then bugs crawl through it there body is cut and they lose their body fluids and die. we have an infestation of grasshoppers this year and it is working to keep them down. best of all there is no residual and does not effect the food. if you use it be sure to get the underside of the leaves.
the formula for your sprayer is 8 tesapoons of dichotomous earth and o teaspoon of dish soap per quart of water.
good luck,
Wiring Man