I prefer to start low-to-mid. My favorite level to start is around 5 or so. While character development is always preferred, I also like to live long enough to get there. When DMing 1st-level characters, they are so very fragile it's sometimes frustrating. The DM and players both have a very narrow margin for error to avoid player death (assuming a campaign with a moderate level of combat), and it's less believable to get players involved with anyone above a certain rank.
How can characters that can be killed by your typical lucky housecat have amassed the skill and reputation to rescue the princess from the dragon? I mean, there's only so many orcs and dire rats a sane mind can fight.
Yes, I know people can get creative with things other than combat, can scale down monsters, and can search alternate sources for more low CR combat challenges, but you get my drift.
Besides, I like to beat up on my players' characters from time to time, and I know some players prefer to be able to give their opponent a good solid thumping. And being able to do this without keeping track of hit-points like a penny-pinching miser makes the game more fun for me.