[Designer or Publisher for Banner creation?]

I need to create a banner design / branding pack that I can quickly adapt for new content, whilst retaining a consistent branding. I also wish to adapt this design to create an e-mailshot that uses the same branding.

I have a range of similar EPS backgrounds and typefaces all ready.

My question is: should I purchase Designer or Publisher to do this, as both seem to be capable.

I am familiar with DTP, but have have never really used illustration packages like Designer or Illustrator. Would using a desktop publishing package such as Publisher be adequate for what I need to do? Or I should I spend time learning a vector design program such as Designer? I am not much of an 'artist' so it is more collating and editing assets into a design rather than creating images from scratch.

Are there any other considerations I should take?

I hope that makes sense.