PokeSpe is great to go after, considering it is the best non-game Pokemon media. There are some other manga which I find to be enjoyable, but have only read a few chapters of:
Pokemon: Diamond and Pearl Adventure! (don't get this confused with Pokemon Adventures: Diamond, Pearl and Platinum, which is technically Pokemon Adventures volumes 30-39)
Pokemon Gold and Silver: The Golden Boys (again, not to be confused with the PokeSpe Gold, Silver and Crystal arc which is vol. 8-14)
Also, Pokemon: Black and White is Pokemon Adventures also. I suggest you read that alongside the normal series.
"It's not who I am inside, but what I do that defines me."- Batman. Started by GreatGonzales