I always use my older bags. I don't care if they don't look exactly like the current crop of bags; but I do insist that they should have elements in common with current fashions and I'll only carry them if I feel they look right with the clothes and colours of the season (or the upcoming season).
Sometimes I'll buy a bag, because I love it, even though it doesn't look right with any of the clothes I'm wearing that season. Even if I don't get around to carrying it much straight away, I don't care, because almost invariably, a year or two later, it looks perfect with everything!
Actually, I think only wearing current season clothes and accessories (without any past season and/or vintage items) can look a touch unimaginative...
ETA: Whoops! Forgot to answer your question about which bags hold up better (from a fashion standpoint) over time - I think it's wise to avoid the 'it' bags (unless you really love one, of course), as they will inevitably tend to look more obviously of a certain season, than a less known style.
Although, if you pack them away and break them out again after 20 years, they will no doubt look perfect again!
