dq8 is not a better game than dq7 in any sense of the word. ps2 version of dq8 blows. You have to wait for the alchemy pot. Added voice acting and orchestrated ost adds load times and ui sluggishness. slower battles. dq8 in general is more padded than 7. In 7, generally things happen for a reason. It has a slow burn to its storytelling. 8? Not so much. When you want to get the ship, enjoy. You'll have to backtrack and do a dungeon just to use it. A lot of the stories feel like filler and the game needed to be edited. There's a part where you can't do something in a castle, so you have to go and get a harp, do a dungeon, go back just to use the harp. So much of 8 is stretched and dragged out for no reason. 7, despite its infamous length, has far more brevity if you can imagine. dq7 also has better stories and writing. dq8 has a plot focus where almost every town/city is ravaged by the villain Dhoulmagus, so it gets boring after a while. It lacks not only 7's emotional highs but also its story variety. Complaining about dq7's slow burn storytelling but giving dq8 a pass is pretty LOL to me.
Mobile version (specicially, ios, not android) is better than dq8 ps2 western version because it's faster, and the alchemy pot is instant like in 9 and a more balanced (read: challenging) game difficulty. dq8 3ds is the best version of the game. It has the added bonuses of dq8 mobile, including instant alchemy pot, added stories, and two bonus characters, and a turbo battle mode. Still highly suggest for a first dq, but if 7 isn't working for you, which is the most story-based dq, then there's small chance dq8 will.
bebpo is also crazy again, dq7 3ds has the fastest battle system in the series.