I'd say Napoli, due to their class attacking force, loyal fan base and low expectations. I'm currently managing Lazio in Serie A, and the league is really fun; there are many class teams in it!
Dortmund, Porto, Ajax, Shakhtar and Celtic will be boring, since you will end up winning the league easily every season (perhaps with the exception of Dortmund, which will be tough but you should be able to win the league).
I don't know anything about Dinamo, but they have little reputation and I find that really boring; you're in Europe and all, but can't seem to sign anyone!
I find teams like Man City, PSG, Malaga boring as there is no sense of achievement, but Malaga would be my second choice here; you could have a go at breaking the Barcelona-Real Madrid monopoly. Hope this helped!
- PZW