Never seen another Sci Fi show match the integrity of B5. I was a huge fan of Moores BSG but as early as the second season it had more plot holes than a chunk of swiss cheese. Never got into "Lost" but heard the same thing. They write fantastic plot devices then write themselves into a corner with no way out. Ive seen other shows where they carelessly ignore important facts set up in earlier episodes. It's somewhat forgivable in a comedy series, but the suspension of disbelief is lost when they are so careless in a drama series which one invests a lot more thought into.
Whether or not you appreciate JMS' writing in general, THIS is how you make an ongoing series with story arcs. I loved how he'd set up mysteries and solve them long before the series ended, but kept the interest by posing new questions before the originals were answered. That way the audience had satisfying closure while still having stuff to follow and look forward to. The series was very well constructed. He approached it like a novel, which is how any creator of a "mystery based" series should do. You shouldn't put up a ton of questions without knowing the answers. Otherwise you get into the same hole as Lost and The X-Files.
The show made television of the past 10 yrs possible:
The season/show -long arcs, and CGI effects done in house. JMS was there first. His secret was to figure it all out before hand so there was no build up to something that could not/would not be paid off in the end.
I'm re-watching the entire series for the first time in a decade. God, I still love this show. So many pertinent themes, long story-arcs, wondersome special f/x...and that music. Makes me feel 20 years younger...