Leverkusen didn't lose any game after 7 rounds and they have only one draw while Bayern got 2 draws and no defeat making Leverkusen in the first rank with 2 points difference from Bayern Munich.
I find Stuttgart interesting too although I doubt they could keep their position at the opposite of Leverkusen.
There is nothing impossible for Stuttgart to become champions in the Bundesliga this year, if I see that Stuttgart has been quite consistent in playing the last 7 matches. Even though they have experienced 1 defeat, apart from that, Stuttgart has a player who is quite consistent in his game, namely Serhou Guirassy as a striker, and has been the top scorer in the last 7 matches. I think Stuttgart will enliven the competition in the Bundesliga in fighting for the title this year, although it is still too early to draw conclusions now.
Serhou Guirassy the player of Stuttgart had a perfect performance so far and in the game, we saw from this player in the Bundesliga he scored many goals. This African palyer scored three goals against Wolfsburg during 15 minutes of the game. Now because of the good performance he had in Stuttgart, his team is still racing on top of the table and maybe there will be many offers for in African play in the next transfer window.