Brussels sprouts are fresher on the stalk than loose.
Locally grown vegetables, in season, are a good bet. However, when you find Brussels sprouts on the stalk, they're probably going to be tasty, wherever they came from. If not on the stalk, check that they are very firm.
Brussels sprouts are cruciferous vegetables, and considered to be healthy food, but they might not taste as good overcooked. Do not make them mushy.
There are various ways to cook Brussels sprouts. The cooked sprouts can retain crispness and not be mushy. It's possible to steam them and get a good result. Boiling them in a pot may not be the best way to cook Brussels sprouts.
There's a pan sauté approach for Brussels sprouts.
Prepare the sprouts by cutting off their bottoms, then rinse, and peel off a few leaves. Cut them in half, lengthwise, unless they're very small. Cook them sauté, in a pan, medium high, with a little oil, butter, salt and pepper. Start a kettle of water to boil, and put the sprouts in the heated pan. The medium high heat, and butter, should brown and glaze the sprouts a little. Be careful to watch at this stage, there's only a minute or so between browned and burnt. Now, turn over your Brussels sprouts, turn the heat down a notch, and add a little boiling water. Then wait a couple minutes and turn the heat down to low.
Cook on low for a few more minutes. If the pan gets dry, add a little boiling water. After a few minutes turn the sprouts over again. With the heat low, wait until the water boils away. Taste a sprout to see if it's done, and check the flavor and seasoning. The sprouts should still be slightly crisp, not mushy, and tasting good. Turn down the heat some more, they will stay OK for a few minutes while you finish preparing other things that will go well with the sprouts, maybe some steak, lamb chops, or liver and onions.