Pretty much all magazines suck, what else is new?
Gamepro's only redeeming feature in its history has been their arcade blowouts where they would detail every move in various fighting games. The rest of the magazine has always been an utter joke. Even the short-lived LamePro was uninspired at best.
I remember the old EGM, what an embarrassment. Every editorial they ever wrote was a Nintendo bash in one way or another. When Super Metroid came out, I remember they couldn't find bad things to say about the game, so they went on endless rants about how crappy the Nintendo corporate structure was and how they didn't get any privileges (they had to buy the games, unlike other companies, who would send them the games for review purposes, or something like that). Quartermann did his best to hype up Sega as much as possible back in the day... he came up with the most insane rumors to get the Sega fanboys excited... Even if biased, that was mildly entertaining. The current magazine is a pile of steaming crap (imho).
Next-Gen was so far up Sony's buttocks it wasn't even funny. I guess they had to make up for Sony depositing subscription cards in every PSX that was released back then. I loved the way they went back and changed N64 scores because they said "We changed our mind, the games weren't THAT good." They jerked off to stupid crap like Prey (which never even came out), and overall made themselves look like idiots. The one redeeming feature of the magazine was the game development article they sometimes put near the back.
GameFan... they had an awesome Japanese games section (except for that one time where some freak started cursing out everything Japanese). Too bad it almost seemed like a Nintendo infomercial at times. They were so enamoured with Nintendo sometimes that some of the ways they defended Nintendo were just utterly spectacular. Again, the only real thing they had was the awesome Japanese games coverage. I liked the editorials generally, since usually they were pretty balanced and focused more on the industry at large. The magazine was still a little too short though. Overall this was probably the best of the multi-platform games magazines.
Nintendo Power... back in the day this was an excellent magazine. I always trusted their review sections. They had absolutely sweet extras, and went all out in their previews. Their posters were really cool too. I think during the N64 era and afterwards, it became a kid's Pokemon Gazette. When I say that, I don't mean Pokemon was for kids. I mean the content in the magazine was geared towards little kids. There were no interesting discussions on strategies used within Pokemon battles, or even news on events that might take place around the area. The magazine in its current state looks like it was written by five year olds. The people who now run and work at Nintendo Power - in my experience - act only slightly older both in terms of their interpersonal skills and their writing ability. They don't even have January bonus issues anymore, and they treat their long-time subscriber base (people like me who have been members since the Nintendo Fun Club newsletter days) without much respect.
Sony's newsletters were not that bad. I always appreciated them because they were short, to the point, and free. They didn't sit and editorialize from what I remember. Even when N64 came out and some newbs thought that Sony was going to stop making games for Playstation (My god that was halarious!), they didn't target Nintendo in the newsletters, instead saying they want to provide a good gaming platform as well. I guess eventually the fan base got so large, that it made it difficult to maintain that. When I bought a PSX for 299, they were also kind enough to send me a free t-shirt, baseball cap, and demo disc for being an early adopter. I wish those people were still around, because even though Sony doesn't have a newsletter/magazine created internally, their current CSRs are incredibly lame and ever since that time period, seem to be filled with fanboys rather than people interested in the customer.
Sega Visions? No articles, just a bunch of random previews and big pictures to get you hyped up about Sega. I never took it seriously, but they did send it to me free for a couple of years.
The only magazine I have the slightest bit of respect for these days is XBN. Even if biased, their articles tend to be pretty good, and instead of turning their content into a pissing match, they make it a point to focus objectively on providing good content for their userbase. Sadly I've heard they are on the way out, but I don't know that for a fact. One of the nicest things about them is that they will even compliment other platforms for their respective strengths. It seems like a very mature group of people in general.
If I missed any relevant magazine let me know... I also remember receiving TuroGrafix16 newsletters and a pilot magazine that was coming out for it a long time ago. Don't really remember too much though. I have a huge library in my house where I have 3 shelves dedicated to gaming magazines. I'll look for it if anyone is interested.