I can talk about Barbados and the Grenadines.
Wind in June is between 15 to 20 knots every single day in the grenadines.
If you are looking for 100% waves go to Barbados.
If you want flat water Union Island.
We also have some great waves in the grenadines but they are located at a 20min ride upwind.
Barbados is better if you want a nightlife more restaurants etc.
Union island is better is you are looking for relaxing very few kiters on the water and everything at a walking distance.
More info on Grenadines: www.kitesurfgrenadines.com
Hope you can find the right place for you.
All the best
PS: if you end up coming to the Grenadines, your flight would have to stop to Barbados on the way so you should use this opportunity to spend some days in Barbados to kite.