We've used Hello Fresh and Gousto, and I prefer Gousto. My husband is vegetarian, and I found the HF options very limited, and usually pasta-based which represented poor value for the price. Gousto has a lot more to choose from, but they do use meat substitutes which are not for everyone.
I found them useful when the kitchen was being done and was out of commission for a while, or at busy times when we weren't sure when we'd be in to cook.
If people are using them for the first time, I recommend getting some fridge boxes and separating the meals into them when they arrive, so all you need to do is take out a box and all the ingredients are ready to go. The meals really do save time, and are much better than ready meals, as you can customise them (eg by adding more or fewer spices) and you know exactly what is going into them.