Pros and Cons of leading HTML and CSS Skinning Combinations

I am trying to build a theme right now for the Spree eCommerce platform for Rails. Because Spree is already a fairly large project, it has chosen a certain set of patterns and frameworks for skinning: Less and YUI. But from reading around on Google, other skinners seem to work faster/better using other frameworks. So I am wondering what the pros and cons are of each so I can spend some quality time mastering one (preferably the one that gets me there the fastest).

• Less vs. Sass - for CSS
• Blueprint vs. YUI - for good CSS defaults and a nice grid system
• HAML vs. HTML - for markup

Spree is using Less with YUI, while most of the blogs posters out there are choosing Sass and Blueprint (which you can use with Compass for automating css compilation).

What are the pros and cons of Less/YUI or Blueprint/Sass?

I would like to just learn and become efficient at one of them immediately so I don't have to split my time between both. I am not looking to use CSS without a framework.

Referencing a discussion on the Spree boards about Getting Started Creating Custo开发者_开发问答m Themes.

I can't really tell you the pros and cons of all of those, as I have not used them all myself. However, one thing I can offer is this:

Replacing HTML with something like HAML, or CSS with something like Sass, can be risky. If you do replace HTML with something else, you require that all future people who work on this project ALSO know HAML. In the case of something like Sass, while it more closely resembles CSS, it is still different enough to be confusing (even highly confusing) to someone not familiar with it.

If I had to choose, I would make a choice fundamentally rooted in maintainability and familiarity. That expands your pool of potential talent in the event you need more human resources, and reduces cost (people don't need to learn something new, and maintenance costs can be lower since you are using profoundly familiar technologies.) Given that, my choices would be Less and HTML. Less is VERY similar to CSS, and nicely blends in variables and mixins and the like without radically changing syntax. I wouldn't choose any alternative to HTML, as there are a zillion people who know it, and very few who know something like HAML or similar products.