Mark, It's sort of tough deciding on good media you really want to last a long time.
If shopping online, the "best" discs you can get will prob. be Taiyo Yuden Premium from supermediastore.com or rima.com. I've not personally ordered TY from either, and there seems to be lots of packaging choices that some people find confusing.
The 3575 seems to like the slower-speeds for dubbing (faster high-speed dubs), so I'd get 8X if I could find them, or 1-16X if not (most readily available everywhere).
Another good choice might be Verbatim 8X if you can find, or again, 1-16X should be readily available. You should be able to find Verbs locally, so easier to return if you get a bad batch.
Whatever you get, make sure you test the first blank before burning and compare the Manufatrurer's ID (MID) to the two web sites on DVD quality (see link to the DVD subject I gave earlier).
I recommend +Rs cuz it's "native" to Philips and they do have a better design for error correction, etc. I remember one long-time user posting his "epiphany" on +R/RWs where he used to get low 90% ratings on his burns with -Rs but got high 90% ratings from +Rs. There only "knock" is they won't have all FF/REW speeds on Pioneer, Panasonic and some other DVD-Video DVDRs (the 3575 is a +VR DVDR... diff. std).
Sorry this can't be a "set in stone" answer, but I don't think there is such a thing in DVD selection. This is a contentious subject here so I'm sure you'll hear from others also.