In my experience newer players are much more likely to focus on what, which can be a big help to them. New gamers, really new to rpgs not just this particular system, seem to do better when they can start with a series of concrete choices (I'm a dwarven fighter), and add backstory once they know what the end result is.
I personally design characters from lots of different angles, depending on what grabs my attention. A friend recently started a campaign using most WotC products, granting each feats, speeding ability score acquisition, and hansding out special abilities randomly selected as characters go up in level. The other three PCs had already been determined to be a warblade, a ranger, and a warlock. I thought to myself "we need a wizard, or a cleric." Then it occurred to me that those three characters are never going to run out of attack abilities, and what they really needed was a utility caster. So, I decided to actually try for a mystic theurge. The house rules are friendly to the idea (extra feats and ability scores makes the split focus easier), and while the character was a weak cleric 2/wizard 2 he could hide behind the other PCs.
Once I had that "hook" lots of other things fell together. I decided to be an elf, and the GM suggested Sun Elf. A roll on my age placed me at 125, with 100 years of that spent in a monestary studying. I ended up using the cloistered cleric and diviner specialist wizard from Unearthed Arcana. The knowledge focus of that worked well with a century of digging through obscure lore and old tomes, and the 16 year old adventurers he's suddenly travelling with soon came to think of him as an ivory tower scholar, with lots of book-learning but little experience. We're all 5th now, and that "who" tag seems pretty well established.
On the other hand I've based characters on costumes, names, themes, bits of background from particular campaigns, fiction characters I enjoyed, and even philosophies. I had what I saw as an interesting view of being lawful evil once, and based a character on that. It happened the campaign had an order of evil-only combat mages, so I worked that into the character, as well as enough backstory to explain where his world-view came from.
As far as I'm concerned, the experiences and attitudes of a group have much more to do with what vs who than the rules system. I've seen Hero players try to decide if they wanted to be a brick, speedster or Batman type before even considering the rules, and I've seen 1st ed D&D players start with quirks of culture and try to shoehorn a fighter into a specific role. Obviously my experiences may be atypical, and rules may skew how many people go with each method, but as long as the end results work for their group I don't see that it matters.