While Bootstrap is "great" it really needs a viable competitor. There's a tons of things that could be done better.
The competitor must be really nice looking by default, responsive, use Stylus/Sass not LESS, and be modular. There isn't one today, but I hope there will be one in 2013.
Zurb Foundation seems to be what you are looking for. It uses SASS and actually predates bootstrap and is being actively maintained. Its a great alternative. http://foundation.zurb.com
Bootstrap came out of Zurb, Mark worked with them and learned everything, and then when he went to Twitter he re-used a bunch of zurb to create the first version of bootstrap.
The thing that finally pushed me off LESS was animations, and the contortions necessary to get to something even approximating DRY for some concepts.
I think it might be a result of trying to be "better CSS" instead of "a language for generating CSS".
Say you wanted to delay a slide-in-right animation for 50ms per list item. (So item 1 slides in immediately, item 2 50ms later, item 3 50ms later, etc.)
For that portion, this is what the LESS looks like:
-animation-delay(@delay) { animation-delay: @delay; ...vendor prefixes... }
.delay-child-animations {
&:nth-child(2n){ .animation-delay: 50ms; }
&:nth-child(3n){ .animation-delay: 100ms; }
&:nth-child(4n){ .animation-delay: 150ms; }
... more things here ...
}
In SASS, we could do something like
@mixin delay-child-animations($max-children: 20) {
@for $i from 1 to $max-children {
&:nth-child(#{$i}n){ .animation-delay: ($i - 1)*50ms;
}
}
"Sass is better on a whole bunch of different fronts, but if you are already happy in LESS, that's cool, at least you are doing yourself a favor by preprocessing."
I really liked Foundation framework. It is responsive by default, now it my first choice for public facing site. Bootstrap I use mainly for for admin interface.
And perhaps focused on the semantic web instead of presentation? A guy here turned me on to the idea, although I'm not sure I yet completely understand how it would go from the abstract to the concrete.
Bootstrap was going to ditch Glyphicons (and IE7 support) with 2.2.2[1] but it looks like they're either holding off on that or they changed their mind. I recommend using Font Awesome[2] instead of Glyphicons.
The competitor must be really nice looking by default, responsive, use Stylus/Sass not LESS, and be modular. There isn't one today, but I hope there will be one in 2013.