Dragon Age Inquisition is the better game.
While I don't agree with all the choices the developers of Dragon Age Inquisition made (e.g. 8 ability limit), I think it deserved its GOTY awards. It's a great game with the best cast of characters in any BioWare game I've played. I definitely recommend finishing the game, skipping the post-credits scene*, then playing the Trespasser DLC. (*I think it's best to skip skip the post-credits scene because it spoils what could have been a great surprise in Trespasser.)
Mass Effect Andromeda was plagued by a rocky development. I think the game is fine, but I expected a lot more from BioWare. After 10 patches it's still riddled with bugs (neither of the sprint modes function properly, navigating menus with a mouse is like climbing a mountain on rollerskates, etc.) It has to be said, though, that the final mission is one of the highlights in the tetralogy for me.
Both games have a design where the main storyline is focused mostly in linear corridor missions with some diversions to bigger areas that mostly serve the secondary content. I think a lot of people give up on these games because they spend too much time in the open areas and lose interest. At one point, the creative director of Dragon Age Inquisition advised players to leave the Hinterlands when they had enough 'power' to unlock the next story mission. So my advice if you're losing interest is to stick to the critical path as much as possible.
