well, since I subscribe to 5 PC mags and 1 mac mag, heres my list:
PC Magazine: Pretty good for the moderately advanced user and below. Experts will find it boring. Reviews of products are rudementary. Content is excellent and I hadly ever get bored reading it.
CPU Magazine: Very good. Good news articles and comparisons, in addition to excellent staff and guest writers. Reviews are very well done. Content is excellent.
Smart Computing: Horrible. Boring magazine and a terrible waste of time to read. CPU Mag. is by the same company, so they are distributed together. Therefore, buy CPU magazine if you can.
Computer Shopper: Good. Some of the articles they write are kind of pointless and really shed no new light on anything. Reviews of products are good. Content is also good.
Maximum PC: Excellent. I personally love reading this magazine, essentially because they focus on what every geek wants... big fast, overclocked rigs, how to get your PC there, and what parts to buy. Their reviews are top-notch and so is their support page. I just recently subscribed to this magazine because I got tired of waiting for it to hit newsstands (it hits news stands towards the middle of the month, though subscriptions usually come before the month even starts.)
I recommend: Maximum PC.