I do a little bit of both....
If it's JSA related...I'll usually pick up the book, or some revamp of a Golden Age character, just to see what's up with it.
Certain creators I follow religiously, no matter what they are working on. Howard Chaykin, Mike Mignola, Alan Moore, Alex Ross, Arthur Adams...
Sometimes, if it's a new title with new character, if the concept or creative team seems interesting, I will pick it up....but this usually comes back and bites me in the ass, because nothing I take a huge amount of interest in lasts all that long, and gets cancelled within about 2 years.
Certain characters I will buy books about, even if I hate the creative team. I buy them just specically for the reason that that specific character is headling the book.
With Marvel...it's usually any book that features any of their Western characters or Sgt. Fury...I can't explain the appeal I find in either, but I can't help myself.
With DC...like I said...if it involves Golden Age characters (especially the Golden Age Vigilante, my personal favorite), or anything that features Kirby's Fourth World stuff.
I seem to have an odd tendency these days of picking up something just because it's presented in a "retro" manner. Some examples of this in the last couple of years have been Marvel's FLASHBACK #-1 books, the Alan Moore 1963 miniseries that he produced over at Image....which probably explains my incredible interest in and the joy I get from reading TOM STRONG, Captain Gravity, and BIG BANG COMICS. I don't know why I like it...I just do.
There are certain characters that I have been a long time fan of, but don't buy their books on a monthly basis...I just pick up an issue or two every 6 or 7 months, just to see what's goin' on with the character. Books that fit this category would be IRON MAN, GREEN LANTERN, THOR, THE AVENGERS, some of the Superman titles, and THE FLASH. All the books in this category I collected on a regular basis in the past, left for some reason, and am usually looking to see if the book is worth buying on a monthly basis again.