All of the Episodes' trailer looked like the designers wanted to try out new things, and how they all work out, that's why we haven't gotten any model that is suitable to all of the trailer. Maybe they want to see which trailer model reaches to most of the players.
Youtube views, thumbs up, down:
Daybreak: 145 443 views, 2,1k ups, 74 downs
This trailer was very serious from the very beginning to the end, very dramatic music really gave this whole trailer this seriousness, and the last, very sad rendition of HoT's theme, kind of brings to my mind that we say farewell to Heart of Thorns, foreshadowing that very serious problems will be revealed- I'm saying those post-factum, didn't know this sad tune would mean such heartbreaking things that happened in this Season so far.
That was a very nice trailer, gave me a touch of seriousness, and that episode was VERY serious. Less joking, more drama. and this trailer was all about the story. and still looked more like Season 3 trailers.
A Bug in the System: 193 768 views, 6k ups, 98 downs
This trailer showed those two sides of GW2's story, with those joke-y animations- one grumpy guardian etc, all spiced up with a nice rendition of GW2 Main theme, and then it went from this crazy part of GW2 to this dark and creepy with this phenomenal Maclaine's version of Fear not This Night. This trailer was an esence of GW2's story, if you ever want to show what GW2 is, post, show this trailer. This trailer is GW2. This trailer was about story, but more in visual sense, the music was telling the story of this trailer, not dialogues
Long Live the Lich: 177 122 views, 4,4k ups, 99 downs
It was basically showing the one character, the main antagonist, to share some wicked insight to this character: Joko. Leading to a big reveal: the roller beetle. It was very one dimensional.
A Star to Guide Us: 111 092 views, 2,6k ups, 70 downs
more recap, than actually showing the actual stuff in the episode. But if you pay attention to the music, you can hear a subtle hint, that something will be very wrong: during Aurene's theme drums appear, and the drums were not originally in this theme. Those drums I think were supposed to give this sense of 'something is not right'. And as it turned out, nothing is alright now. Play Ep 4 to find out! so basically this trailer was more focused on some slight, almost unnoticable things, much more mysterious and giving no clue where the story is going.
So, which style should be used more often?
Seek, and you shall find.