Seems the Wii doesn't care about booktype, but of course, it never hurts to set it to DVD-ROM
I suspect DVD-R DL (which as all -R media can not have the booktype changed ... this can only be done in +R media) might be the one that gives the most problems BUT, when it works for you, that is, happens to work on your burner-blank media-software-recording speed combination, probably produces the best burns.
So it probably works for fewer people, but for those that works, works very well. +R type media probably works for more people, but probably results on discs that are a tad harder to read by the Wii.
This is just what I SUSPECT. No proof, no insurance, no nothing. Just what someone with some experience but not too much on these subjects THINKS or have read, but hasn't proved or tested by myself.
If you wanna know what I'm gonna do myself: I'm gonna shell out $35 and get myself a new burner. Pioneer has some new models coming out this month, so I'm gonna wait a bit to read the reviews on those. If they suck on the reviews (a LOT of times newer drives work WORSE than older models, so newer models are no insurance of a better success rate), then I'll get myself that Samsumg everyone raves about HN23 or something, (can't remember, just google for burner reviews). If people say the new Pioneers are good, I'll probably go for one of those (a tad more expensive, I think, but still under $50 bucks). And will stick with Verbatim media +R media only, as it works on my Xbox360, but will keep on buying other brands and testing everynow and then to see if I can find another brand that doesn't give me many coasters.