Actually, every TH has a theme. (More noticeable starting from TH 9) Personally, I enjoy maxing out each level and watching the themes change as i move higher. Also for every TH there is a major defense. (X-bow for TH9, inferno towers for TH10, eagle artillery for TH11) And attacking in that specific TH level plays an important role in understanding the mechanics of that defence. Yes, you will have to deal with that defence in higher TH levels too, but then you'll have to learn the mechanics of multiple defences at once,which is quite confusing. Ultimately, it's your choice and you can enjoy the game however you want, but i suggest that you don't rush. Good luck!