Firstly I wouldn’t put Bayer Leverkusen In the same category with Girona and Bologna in the champions league. Yes they haven’t won it but they are very much familiar with the competition, they have even in the last few years been in the competition more than even Aston Villa who had won it in the past. It will be a mixed feeling for First time Girona, maybe they will push harder to the quarterfinals like Leicester did when they came or fall fiat like Union Berlin
This season there are many surprising teams in the league that will compete in the Champions League next season, some debut teams will feel how tight the competition in the Champions League is, as well as teams that have been absent for a long time in the Champions League and will again feel the competition among the best clubs in Europe, Leverkusen who have appeared surprisingly this season of course will try again to repeat their history of being able to reach the final like in 2002, so with Leverkusen performance and performance this season, of course we cannot underestimate them in the Champions League next season, especially since Leverkusen is indeed a team that has a lot of experience in the Champions League compared to other surprise teams this season, so indeed we cannot deny that Leverkusen is several levels even above Aston Villa, Girona and Atlanta.
Girona, of course a Spanish underdog team that will try to have its first season in the Champions League, but whether or not Girona is ready to compete in the Champions League will depend on their squad, currently Girona of course has a pretty good squad competing in La Liga, but to compete in the Champions League next season of course they still have to make a lot of improvements to their squad, In my opinion, among the surprise teams that you mentioned, of course Leverkusen is the team that has the most chance of going far compared to other teams.