It is very likely that you have a preference for certain types of games. Some people prefer sports games while others prefer shooters. Chances are that there is even a series that you just can't do without. It is important that you do not end up with a nice new shiny console but the games you like to play are not available for your console.
It is important that you research what the consoles can deliver in terms of performance so that you are not disappointed afterwards. If you are a power user you don't want to end up with a console that does not live up to your expectations.
Think about how much money you are willing to spend to buy a game console. Gaming costs money, not only the initial costs for the console but also the games and peripherals.
You will want to avoid spending more than your budget permits. You do not want to be in a position that you can't afford to buy the game you were waiting for a long time for when it is finally released.
Most consoles offer an online service. Both the cost and what is included in these servers vary. If you are going to play online a lot, you will want the best service available. Stable servers, no downtime and cloud storage.
The way your data is stored and the maximum disk capacity are very important.
If you plan on buying digital versions of games, you might run out of disk space very quickly. With the PlayStation, it is very easy to add some extra storage with an SSD (solid state drive).
What console are your friends playing on? Chances are you want to play online with them. Having the same console as your friends have a lot of advantages. One of which is that you can borrow that game that they already finished for example.