Which HTML is good for Designing? HTML4 or xHTML1

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We know that there are many HTML versions and Standards.. Please tell me which HTML is better or easy or good for Webdesign.. xHTML does not recommend the use of B , I and U for the Bold, Italics and Underline for formatting the texts.. I think the U Underline tag is removed from xHTML and recommend to use CSS for it.. Which one do you use and which one do you suggest?