Leverkusen is a good team with team work I must say, but rating them above teams like Manchester City, Barcelona, Inter Milan, and other big teams in the Champions League is not proper because these teams can do better than Leverkusen in the Champions League.
On the other hand, Leverkusen can still display and outstanding performance in the Champions Next season just as they did in the Europa League, but it will be very difficult for them to reach the final.
Next season, they'll have to defend their title as well as live up to the expectations of their club fans of which I think will be more demanding than that of last season. Bayer Leverkusen in my own opinion will do well in the UEFA Champions League competition but I don't think they'll be able to go past the quarter final stage of the competition.