I'll have to look for this one "GT Purely Porsche"

GT Purely Porsche has great photography, but I find the mag itself boring. I generally only buy it if it has an article on a specific car that I'm interested in like the 917 or something.

My regulars

Excellence -- best 911 mag (there's a new one, but I haven't seen it anywhere yet to compare)
Road & Track -- Best US car mag, Peter Egan rocks
Octane -- UK mag with really interesting stuff about classics
Motorsport -- UK mag with great articles about classics

I also like Vintage Motorsport and occasionally grab EVO, I'd probably have a subscription to both as well as the 4 above, but the wife put here foot down on my monthly magazine spending, so I had to cut it down to 4 subscriptions plus the occasional one off the shelf.