Go to a newsstand and look at each of them. Order which one you like best.
If I post here is because I would like to know others opinions.
If you ask for others' opinions, how exactly does that help you make your decision? Any of the magazines you mention have been around and can be considered "good" by various individuals. Other people telling you what they like does not mean that you will share their opinion.
Who are you to know what will help me or not?
Don't want to share your opinion, be quiet.
This'll be a big help: I subscribe to both MacWorld and Mac|Life.
Of the two, though, I've lately been enjoying Mac|Life more.
OP: While I agree someone else's opinion shouldn't affect how you like a single issue, it can certainly be helpful when committing to a subscription. You're asking about a track record - and since you can't flip through a years worth of issues at the newsstand, someone else's opinion is valuable. That's my opinion, anyway...