In my opinion category of good coin is look from their team founder should consist of people who professional and transparan and they has working product already. By they has working product that mean the team really serious to development their project. Then other one is aim of the project and what problem will be solved. If their project really can solved some problem then many people will be interesting in it and buy the token so the price of token also will be increasing.
Yeah, the team will really keep doing a good job to keep the ball rolling and trying as much as possible to stay relevant. There are some coins that are really not worth holding for long as you won't even hear a single thing from the devs once the coin is launched and you are strictly going to be on your own. Those categories of coins end up becoming shit coins at the end, and no one will like being a bag holder of such coins.
I suggest you in coinmarketcap you will get detail info about coins.
Coinmarketcap can only give you good direction of coins to research on based on their market caps, but when it comes to long term holding, just as it sounds, you really need to be sure the project is really going to be able to stand the test of time. Not all the coins you see at the top today are going to remain there and some will get being pushed down the more which is normal considering how big the market is.