This article is from the rec.arts.sf.written FAQ, by Evelyn C. Leeper evelynleeper@geocities.com with numerous contributions by others.
The three most widely distributed [fiction] magazines are ANALOG,
ASIMOVS, and F&SF. They concentrate (roughly speaking) on "hard SF",
character-driven SF/fantasy, and literary SF/fantasy. Your best bet is
to try a couple of issues of each and see which you like.
There are also several other magazines not as visible. SF AGE has a
mix of fiction and non-fiction articles on film, gaming, etc. Someone
said that REALMS OF FANTASY has the highest circulation of any SF
fiction magazine, but I have to confirm this. INTERZONE focuses on
British science fiction (not surprising, as it comes from Britain).
ABORIGINAL is not, as you might think, Australian, but American.
AUREALIS and EIDOLON are Australian.
 
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