There are many factors that makes the altcoin valuable.

First is the team behind it including the advisers. In my experience, the one who has a highly reputable person in their team are those who are reaching their hard cap easily in their crowdsale. I'm not saying that all but most of them.

Second is the project itself, if it helps people or if it is working. If their project is good and if it benefits the people then definitely they will invest.

Third is the transparency of the team. They must show their true profile and they must not hide something because if they will do it then it will be a bad sign for the investors.

Fourth is their roadmap. Fifth is their technology. How many tx per second their coin will do? What will be the use of the coin in their project? In their platform etc.

Last for me and one of the most important is their marketing strategy. How they can market their product in the online world.

This will help them in achieving their goal in the future.