Some gamemodes are less popular, some hours of the day are less popular, with ranked you may be at a rank where there are fewer players for the matchmaking to pair you with. Basically, matchmaking times can vary a lot.
Thanks for the replies. Is strength of the deck a factor whatsoever? If I just want to play to complete a quest it seems silly that simply because I have no life and play the game casually while sitting around I have to wait longer for gaining rank through inheritance. I'd gladly just play a base deck, especially to speed up the quests