Here via freaknation
. I got into the fandom after the show was cancelled, so I can only speak to that. Also, I am an Alec fan (and a Max/Alec shipper), I watched season 1, but Alec was my in into the show, to admit all my biases. Of course, people respond to characters differently - have favourite characters, and the writing on Dark Angel could be, er, inconsistent, which doesn't help. But I really do think that - from what I've seen, and again that's coming from a different experience - the feelings about characters have been entrenched by shipping positions. Max/Logan and Max./Alec are the two main ships of the fandom, and as canon kinda sorta played on the love triangle late in season 2, before the show got cancelled, plus there's some season 1 vs. season 2 debate, it got pretty divisive.
In all honesty, there is animosity towards other characters among Alec fans. I think quite a lot of the vitriol towards Logan is because he's the canonical love interest, the problems the fans have with the way that was depicted but also, quite simply, because he's the rival to the Max/Alec ship.
Ditto for Alec in the Max/Logan 'ship. I mean, even if you don't go for the interpretation that there was something there between Max and Alec beyond the level of comrade, it's widely known in the fandom that some of the show creators wanted to delve further into the love triangle, and in terms of the fic output, there's a lot of Max/ALec being written. Max/White, Max/Zach and other pairings are very niche - I'm using ff.net as my barometer here.
Sorry, that was a digression. Like natasqi
described, there's also a lot of Max-bashing, some of which comes out of frustrations with the way Max was written (I like the idea that Alec was a second attempt at the transgenic Max once was, trying to work out how to live in the human world). Some of it is childish Alec is my favourite thus he has to be the best at everything. I dislike out and out bashing (unless if it reaches the intentionally funny) never mind the character. I will admit that what you as a Logan or Max/Logan fan might call shades of bashing, i'd take on board as within the bounds of reasonable interpretation, especially if it was within a cracking story.
But a lot of the fannish interpretations of characters are, to be honest, more based on fic than the show at this point. so much fic has been written and consumed, and shippers are writing for other shippers, so more assumptions are made and tropes repeated, and a certain view develops that is a fair bit away from canon.
I think someone else pointed out that Max's irritation with Alec is also partly because he looks like Ben. i think there's also the point that some of his criticisms of her are a little too telling - he is her equal and doesn't feel the need to soft-pedal with her. (I would also say that there are other things going on, but then I'm a M/A shipper.)
On Alec/Asha, I went through a phase where I thought that I would write one, but after the revelations of 'The Berrisford Agenda', I really can't ship Alec off with a non-transgenic. When he was interested, she wasn't and after that, he's deep into the mindset that relationships with humans are dangerous. I think he'd still take a none night stand, but because Asha's now a friend, he couldn't go there.
And...that was long, and possibly rambly, but I'm all yay! Dark Angel meta.