Is there one that defaults to block
defaults to inlineinline-
In principle, it depends on the browser what the default value for the display property is for each element. Even HTML5 drafts do not prescribe what values must be used, though it presents “expected rendering” of elements in terms of CSS.
According the default style sheet for HTML in the CSS 2.1 specification, the elements that have display: inline-block by default are button, input, select, and textarea. Browsers use such settings, except that in Firefox, this only applies to button and select.
In the Rendering section of HTML5 CR, the meter and progress elements are additionally describes as having inline block as “expected rendering”, and browsers that have implemented these elements appear to behave that way. The keygen element is also described as being an inline block, but Firefox does not do that (it implemented keygen internally as select in the DOM); IE does not support keygen at all; Chrome implements it as suggested.
Since all of these elements have rather specialized meanings, functionality, and rendering idiosyncracies, none of them is adequate for general use as an element that is an inline block by default and may have various meanings. What you can use for such an element is normally span or div, depending on whether you prefer inline or block as the default rendering.