I teach piano lessons as a side job, and one of the questions that I get asked regularly is what sort of keyboard or digital piano should parents buy for their kids. Of course, the answer to this question depends upon what you are looking for and what level your child is currently playing at. If the child is just beginning, then I would probably suggest the alesis recital 88-key or something even less expensive. If the child is more advanced, then they might prefer to spend a little bit of extra money to get them something that will last them a long time and give them the perfect sound. For the more advanced child, you could be looking at spending anywhere from five-hundred dollars to a couple of thousand. In that case, the decision might primarily come down to what you can possibly afford.
For those who do buy something like the Alesis recital 88-key, there is very little risk. The keyboard is not very expensive, but it does provide the child with all of the essentials that they need in order to get better at playing. Something like that will give the child decent sound, and the keys, while not perfect, will at least partially simulate the actual keys of a piano. Of course, those keys do lack a little something when compared to the keys of more expensive digital pianos, but for a child who is just learning how to play it actually works quite well for them.
The children I teach do, of course, come to my home and practice on my baby grand, so if they are not at least somewhat familiar with the weight of actual piano keys, it can cause them a few problems. This is why I would never suggest one of the cheaper toy keyboards. If the family wants the child to be able to figure out how to play as quickly as possible with a relatively small learning curve, then the most realistic thing that they can get at home is preferable. Of course, this also does not mean that families with children who are just figuring out how to play ought to break the bank in order to give their kids something that they can play at home.
Ultimately, it really comes down to the level that the child is playing at and the amount of money that the parents are willing to spend. I often give my advice in this regard, but I also know that there is a lot of subjectivity when it comes to making such a decision. In the end, the parents will have to figure it out for themselves.
Either way, so long as a child has a keyboard that will allow them to practice while they are at home, they will be able to get better. The best beginner keyboard is one that provides a lot of positives without having a huge price tag slapped on it.