Believe it or not, though I live in a cooler climate - called temperate - the vegetable that I find the most reliable and consistent is the cucurbita family - courgette(zucchini), pumpkin, summer and winter squash - no problem to grow, just to get the seed started under heat, is a small challenge. Amazing growth and production, though.
What others have said about the root veggies and the lettuce family is also true - very easy and good production, though I do have to look out for pests, in particular the slugs!
The good old potato is also a very reliable veg that crops well.
Also the ease of some fruit growing can't be overlooked - strawberries and raspberries.
The greens I find the greatest ease with are the chard variety - very productive and the birds and pigeons don't like them, nor the slugs and they can last through to next spring if the winter isn't too harsh. If I plant good old cabbage, though easy to grow, young plants can disappear overnight - slugs, pigeons and in July, caterpillars. A nightmare to look after, until the cooler weather sets and all the pests disappear.
Thanks for the question.