De gustibus non est disputandum: In matters of taste, there is no argument.
This might be the case for cooked greens, too, but I do believe most resistance to them comes from being served overcooked greens. Sure, creamed spinach might have a special place in one’s heart (it does in mine), but goodness, serving all greens that way would be like boiling one’s broccoli or asparagus or green beans into submission: it’s not recommended!
As far as I am concerned, there are two steps to cooking delicious greens: 1. growing your own and 2. cooking them to the proper consistency as dictated by their texture. Step one is pretty obvious. If you grow your own you have enormous incentive to eat them and they’ll be at the peak of freshness. Step two is a bit more tricky, as it requires a bit of consideration of the leaves. But even that gets pretty easy: the tenderer the leaves, the gentler their cooking.
Warm spinach salad: Wash and dry some new spinach (if there are thick stems, remove them), and place in a glass bowl, and add some crumbles of feta cheese on top. Heat some good olive oil to just shy of smoking: you just want the sweet flavor to leap out. You may add some chopped chives or very thinly sliced garlic at the very end of heating. Whisk in some good balsamic vinegar or lemon juice, and add a pinch of salt and some pepper. Toss over the spinach and adjust seasonings: the spinach should be slightly limp, and shiny, but not cooked. Serve warm.
(Warm salads are entirely adaptable: saute some cubed marinated tofu in some garlic and sesame oil and ginger, and toss them, hot, with clean, slightly damp spinach. Same with lentils, or other savory beans: toss hot, eat warm.)
Bigger, tougher leaves require bigger, tougher care. Many greens through the heat of summer have thicker stems and more leathery leaves: this helps them conserve their energies; this adaptation one of the reasons you won’t find spinach grow for you in the summer! Often, I cut or pull the leaves off the tough ribs and stems and chop the ribs to cook separately. It is here I pull out what my family considers to be the Great Equalizer in making any green palatable: plenty of representation from the genus allium. So, I will chop up the summer-toughened stems of kale, rapini, chard, etc. and throw them in a pan with plenty of onions, leek, and/or garlic; add a glug of olive oil and some salt, and caramelize them together gently. After they look mostly cooked, I add the chopped leaves and a bit of water, cover, and cook; checking on them until they’re (what I consider to be) done. A splash of vinegar at the end brightens them up a bit.
Many greens are from the brassica family (cabbage, kales, rapini, bok choy, turnips, collards) and so share that family’s somewhat offensive sulfurous stink when cooked. Some studies say the longer these things are cooked, the more hydrogen sulfide is released! It is traditional, however, to boil to death certain collards and mustard greens: simmering in a pot with some garlic and maybe a ham hock…frankly, I *love* Southern greens, served up with some butter beans and a side of thick bread to sop up that “pot likker,” but perhaps this is an acquired taste. Actually, many collards and mustards grow so thick and hearty that a long simmering is the only way to make them edible.
Anyway, experiment lots is the best advice I can give you with greens. Experiment, and have plenty of garlic and onions on hand…