The normal, main shared universe for Marvel Comics has a lot of good things about it from several decades of writing and character development, with a deep background to call forth for future revisits of various plots and villains. But, the very fact that they have such a deep-seated background works against them. The time process of most superhero comics is very skewed over a long period of time, and events that took place more than half a century ago in chronological print only seen as having mere years, at the most, pass within the in-continuity timeline. Therefore, although Sue Storm and Reed Richards had their daughter Valarie more than a decade ago, her age isn’t even that of a decade old.
I can understand the process and the reasons why, but I personally dislike the situation. It requires the reader to look far back into the publication’s past to get the first-hand experience of the situation that is very often later used in more up-to-date issues. But, the great thing about the Ultimate universe is that it was only established after the turn of the century, and therefore it is easy to go back and catch up on it. So easy that I was able to read the entirety of the Ultimate imprint within a handful of weeks, and the one thing I gleamed from that experience is that, ultimately (pun intended), the Ultimate line is superior to that of the “normal” universe in several ways.
The storytelling is better, in my opinion. As established above, the main universe has a decades-long background that it voluntarily draws upon, but almost does so as a requirement to keep true to the characters and their original situations. Sure, characters have developed and progressed over time—Peter Parker now teaches school instead of going to it, Bruce Banner is not a mindless rampage when he’s in Hulk form, and Charles Xavier can actually walk now—but the core of who they are remains standard. There’s a formula that the writers and artists stick to; however, in the Ultimate universe, several things are different, and some of the most attention-grabbing events have taken place, which really shake up the way things are. Parker is killed, Magneto actually succeeds in a mass-destruction scheme, the X-Men are more or less wiped out, the Fantastic Four is disbanded, and Captain America quits, not things that happen within the main universe.
The artwork is also fantastic, better than a lot of what is seen in the main universe. Very dark and gritty, with rough edges to make it feel different. But, to be honest, the art is always a secondary concern for me; if I can’t get behind a story, despite how good (or bad) the art is, then I just can’t get into it. But, what really sticks out for me above all is that the Ultimate universe isn’t overflowing with titles. The most it had for regular, ongoing series at any one times was four (three currently); the main universe has more than 20, not to mention all of the limited series and one-shots. It’s just too big with too long of a history behind it.
So, for any new readers to the world of Marvel, in general, I really would suggest that you focus more on the Ultimate imprint and then try to pick up some of the main universe titles. Chances are you’re going to enjoy the Ultimate lines better, and if you try to go back and read the massive archives of the main universe, then be sure to write out a will, for you’re just asking to kill yourself with all of that reading.