With Unicode and the demand for greater multilingual support, in general, a lot of character sets have been rendered obsolete (MacRoman or ANSI) or, perhaps, insufficient like ISO 8859-1 and Windows 1252 - to name just two "Western" sets.
As with any software, defaults matter a lot. For example: what would you recommend newbie type designer load up in their font editor when making their first font?
(I'm asking because I've been writing HTML web font test pages. And some of them test for compliance with the major character sets like WGL4 and Adobe Latin 4, to name two. Also, these pages take a different approach to testing than anything else currently available. Among other benefits, they are easier for type designers to insert into their work flow because they sit in your local hard drive's file system. No web server necessary. They will be offered as open source and free of charge. So the smarter you make me, the smarter I can make tools for you.)
So, what set do you pick first, out of habit?