I know Dragonspine is OP but it sounds short to have that haste for 10 sec. If i get a cc or a cc chain then its like nothing. However Berserker's Call has 20 sec burst window and u can time it. I'm not focusing this 2 trinkets ive just wanted to give you an example i cant decide which choice is the better.
Generally speaking, on-use trinkets are better choice than proc based because of the reason you mentioned.
It also depends on where do you want to use it.
It doesn't matter that much in BGs but in arenas you'd be probably aiming for Berserker's Call or Battlemaster's trinket.
I can't remember of any better for a little kitten now.