I guess that's debatable, but I nearly always opt for boots + 3 pots. If you get a dring, you can't trade for shit, whereas I have 450+ health worth of pots to use. AP vs AP is always about the burst kill, and if you're walking around with 60-70% health at level 6, you're either going to be forced back or killed. The flat +100 hp is nice, but the pots are also great, and I can build my boots where as a dring is a deadweight. This also puts you into the cycle of having to buy more drings, so you can stay competitive in the lane. Mana regen is laregly unnecessary for most AP mids, and most mages dont have much use for yellow seals beyond mp5, which is more than enough (i actually just put armor seals there, and still have no problems). And +10 AP? Bonus damage is the most overrated aspect of LoL, IMO.
Boots also help the player more easily avoid skill shot heavy AP mids like Brand, Xerath, Swain, etc...
I used to play dring with a powerful AP rune page, now I walk into lane with boots, 3 health pots, and ~60 magic resist to start. It's a free win on the lane for me if they grab the dring. I laugh when I see people walking around with 40+ AP to start, a dring, and a measly 30 MR. If you're doing dring, I'd say the only way for it to be effective is to build a defensive rune page.