I did a combination of whole foods and calories counting. Calories definitely count - 4000 calories of walnuts is super healthy AND 4000 calories!
When I was losing weight, I did count most calories very carefully, but I tended to estimate the "salad" type vegetables. Spinach, broccoli, onions, zucchini, summer squash, tomatoes - I never limited any vegetable like that and gave it a very rough estimate. For example, if I made a salad - it was a HUGE mixing bowl of greens, tomatoes, onions, carrots with a measured 2 tbs of sunflower seeds, a measured 2 tbs of light dressing and a measured portion of protein (tuna, chicken, turkey etc).
I did carefully count/weigh/measure healthy but more calorie-laden vegetables like beans, sweet potatoes, corn.
I still measure foods that I find difficult to eyeball, but really need to be portion controlled like brown rice, whole grain pasta, nuts, dried fruit, cereal, granola, etc.
It definitely isn't impossible to eat 2500 calories of whole foods - some of the most delicious and good for you foods are high in calories and healthy fats - avocado, olive oil, walnuts, etc. Give me some fresh, bakery whole grain bread and a jar of natural peanut butter and I could easily blow 1000 calories before stopping to take a breath. That's why it's necessary for me to stay mindful with my food choices - whether it's a donut or a carrot stick - I try to always be aware what I'm eating and how it fits into my daily plan.
I would definitely recommend the whole foods/calorie counting approach - you will feel great, have tons of energy, be eating foods that can help you stay young longer, prevent disease and be able to eat a greater volume of food to stay full and satisfied