Which one to choose and why?

I'm at the beginning of a really large web dev project, and the team I am on are trying to figure which DocType to go with. We will be developing with WC3 best practices along with heavy accessability.

So it seems to me we have the following choices;

HTML 4.01 Transitional
HTML 4.01 Strict

XHTML 1.0 Transitional
XHTML 1.0 Strict
XHTML 1.1

I would prefer to stick to 'Strict', as we will be developing with accessibility in mind and I believe that will ensure we stick to those standards, but I'm not sure. What is the benefit of either one of these over the other? I'm thinking of just going with xhtml 1.0 Strict and be done with it.

HTML 4.01 Strict

How come? I don't understand why html 4.01 Strict would be a better choice than xhtml 1.0 Strict, or xhtml 1.1

The commonest browsers around do not understand XHTML, so they translate is as html. It is a very common misunderstanding to think that XHTML is the "modern" way to design web sites. There are no advantages to using XHTML. It just has stricter rules about closing all tags

http://24ways.org/2005/transitional-vs-strict-markup
http://accessites.org/site/2006/09/i...-doctypes/#n23
http://www.webmasterworld.com/forum21/6706.htm

Use HTML 4.01 strict.

As Transitional was intended as a half way house to help older web designers used to HTML 3 (!) make the transition to html 4, it should not be used now. It allows you to mix css styling with the deprecated inline formatting from html 3. But as no sensible web designer should be using inline styling and especially deprecated ones, and you can't set the deprecated styles in a css file, then using transitional is a waste of time.

XHTML 1.0 Strict

Yes, some browsers don't understand the correct usage of XHTML, but although it is parsed as HTML, the XHTML (which is better structured as it's based on XML) will give far cleaner and more understandable code even if read by some browsers as HTML.

XHTML 1.1 isn't adopted well enough to really start using it yet.

right on, good info. thanks! I'll be suggesting html 4.01 Strict then I think.

HTML 5 is due 'out' soon anyway. It makes little difference to the end user as long as it's valid, remember that when you get doctype errors

when you say soon...is that like 5 years from now soon? I've been waiting for CS3 for what seems like years now (same with html 5).

Probably, yes. I'm just seeing a lot more about it. Looks good though for instance we'll get tags like:

<header></header>
<content></content>
<inset></inset> (sidebar they mean)

It's going to annoy a lot of people though, so many folk are still learning CSS 2.

HTML5

The new TAGS are semantically accurate NAMES for their intended purpose - to hold content that you wish to refer to as header text, footer text, address text. etc.

HOW you position them on the page and style them will still be done by CSS. Using a <header> or <content> tag will not result in it replacing the css rules that you use to position things on the page.

How will you define the background colour for <header>? Using CSS.
How will you define the borders for <header>? Using CSS.
How will you define the width for <header>? Using CSS.
Min-width? Max-width? Background image? Floated?

And so on.

Give them another two years or so to finalise the working draft, to release it as a spec.
Give the browsers another two years to adopt the rules. All the rules might take longer.
Give the users another two - three years to upgrade their browsers.

Then start using it.

Pencil in 1st January 2015 as HTML5 day !