I am lactose intolerant. How can I prepare a good cup of coffee with milk? I don't like the taste of black coffee. I usually use soy-milk, but it is nowhere near original milk in taste.
Try frothing the soy milk with a hand-held frother, even if you just slightly froth it.
According to this Milk Frothing Guide
Incorporating air into the milk improves and sweetens the taste. Milk that has not been foamed at all tends to taste flat and dull by comparison.
Also consider experimenting with other kinds of milk substitutes: almond milk, almond-cashew milk, coconut milk, hazelnut milk, hemp milk, oat milk, and rice milk.
Update: I've found that I like oat milk the best. It should be feasible to make oat milk, but I haven't tried that yet.
Personally I love almond milk in hot drinks. Though I usually use soy milk with coffee, I love to have almond milk chai. That's a tea drink, but maybe it will do it for you in coffee. I recommend it because it's usually touted as a good cow's milk alternative
I would also recommend trying different "alternative" milks to find what you like. In the way you might not like soy milk, I don't like coconut milk in drinks, but other people swear by it. Rice and oat milk are pretty good in my opinion, however.
I'll say this, though: If you go a while without consuming dairy (say a year), your taste palate will change. This is a commonly reported phenomenon among vegans and lactose intolerant people who stop consuming dairy. I can testify personally that I can no longer stand the taste of milk or cheese, and I'm five years "plant based".