There are lots of well-known great kite spots around the world.
Tarifa, Dakhla, Cape Town, Cabarete. These are a few of them, but they're not all great for foiling. Ever seen a foil video from Cape Town? Definitely not very many of them.
traditional kitespots value different things than ideal foil spots:
"Butter flat" water. This doesn't matter on a foil. "Flattish" water is nice, but small chop makes no difference. The problem with a lot of "butter flat" spots is they're too shallow for a foil.
Depth. As mentioned above, shallow water is great for learning to ride a twintip, but bad for foiling.
Waves. Wave foiling is growing, and it's fun, but the types of waves that are good for foiling are different than the types of waves that are good on a surfboard. Sectiony beachbreaks are almost impossible on a foil. On the other hand, rolling swells are great for foiling, but sort of boring on a regular surfboard.
Seaweed. Seaweed doesn't really matter at all on a twintip, and just barely on a surfboard, but it ruins foiling.
Wind conditions. A lot of traditional world class spots are known for regular winds in the 2030 knot range or even higher. Spots that usually blow 12-15 knots are sort of overlooked, but this is plenty of wind for most foilers, and it doesn't make the water and waves so choppy.
There may be other conditions I've overlooked, mention them below if I've forgotten them! And of course there are other things that make any type of kiting more fun. Warm sun, crystal clear water, etc.
So, I'll throw out a few here. I'm only going to include places I've actually been, I want to here where you've been that's great for foiling, too!
USA - Hood River, OR
The gorge is well known for being super windy. And it often is. The foil culture that's emerging in the gorge is all about 5m surf kites. We use a lot of 5/6/7m kites all summer long. The gorge isn't known as a great flat water spot (despite the slider park), but it's a lot flatter than a lot of other place in the world when it's blowing 20 knots. I never loved riding river swell on a surfboard, because it's not quite like a real breaking ocean wave, but it's great on a foil. Also, the gorge has great scenery, and the foil is a great vehicle for exploring up and down the river if you're feeling adventurous.
Dominican Republic - Cabarete
When it's windy, the chop can come up in Cabarete, and it can blow seaweed in from who knows where, which makes for mediocre foil conditions, but especially early in the day, when the wind is first coming up, Cabarete is a great foil spot. Clear blue water, open space to look around, steady sea breeze, and great reefs for practicing wave foiling because you can always turn turn the beach and run to the flat water bay inside. When first coming to Cabarete I expected a mostly twin tip spot, but I actually think it's better for a surfboard or foil.
Italy - Talamone
A relatively light wind spot, but no problem on the foil, Talamone is an amazingly gorgeous bay. You can explore the bay in relatively flat water as the fetch is relatively short to the Mediterranean with Corsica and some other islands not too far offshore. It's a beautiful place to foil, with the main downside being that the shallow slope of the beach means you need to walk quite far out to water start, and you need to watch out for urchins.
Maybe that's enough to get people started. Where are your favorite foil spots?