Just to add on what the other said. T20 is the spectator-friendly version of cricket where it's all boom, boom, boom and it is where the big money is, especially the IPL.
Cricket purists will always prefer international Test cricket, the matches that last 5 days. They also happen to be the most 'boring' to non-fans.
The strategy in T20 is to hit the ball as hard as you can and try to score as much as possible. 50 overs cricket is going the same way in general. Batsmen are the stars of T20 and 50 overs, bowlers would dominate more in test cricket because of fielding restrictions. There are far more restrictions in the formats with less overs for bowlers and fielders. In T20 and 50 overs cricket having a bowler that can make a difference is essential. In Test cricket, having patient batsmen who can build up scores is essential. The basics are the same but the nuances are vastly different.
Which is specifically for the entertainment factor and getting bums on seats and tv audiences.
There will be a Test World Cup starting soon which personally I can't wait to see. I also follow the T20 and 50 overs World Cups.
tl;dr T20 and 50 overs is spectacular with batsmen dominating. Test cricket is far more tactical and usually the bowlers dominate (bar Steve Smith and Virat Kohli). In T20/50 overs, having a deep batting lineup with power-hitters is essential. In Test cricket, having bowlers that can take wickets is essential.