If we go by comparisons, Babylon 5 is like a cross between a slightly grittier DS9 and a slightly more light-hearted Battlestar Galactica (Ronald D. Moore version).
It aims to be epic, dramatic, political, somewhat realistic and sometimes - but not always - dark (a frequent criticism of B5 is that its humour is - except for the Londo/G'Kar stuff? - often pretty cheesy, so it's a show which is great when it goes dark, but sucks when it tries to be funny
Stargate SG-1 is maybe closest to Star Trek: TOS... only set in the 90s, and with a long-range "transporter" (the Stargate) instead of a starship? SG-1 is mostly a action-adventure show which doesn't take itself too serious with some tonge-in cheek humour. But it doesn't fail when it does drama too.
Personally, I prefer B5... but that's just a matter of taste.