If you are staying with 16 series chips then I would suggest the following,
18 pin - 16F88
28 pin - 16F886 (876A with internal oscillator)
40 pin - 16F887
Although, there is very little example code for these (on the internet) as they are the newest chips, the modifications required to get anything working are very minimal and plenty of posters here will help. However, if you intend locking yourself away and going through tutorials, you may be better off with the 16F628A, 16F876A and 16F877A.
Mike.