While I stick to one brand of albums for my main 12x12 albums (Pioneer) I have ventured out into other brands (Doodlebug, WRMK, AC, Hobby Lobby brand) for other projects the last couple of years--the only brand that I have come across that doesn't fit with the vast majority of page protectors is Colorbok. I bought a Colorbok album (Big Lots?) and was PO'd to find out their holes didn't match up with the extra page protectors I normally buy. Fortunately I was able to find extra pages here on SB.com so I can still use the album!
Now if you are looking at anything smaller than 12x12 (or probably 8.5x11), that's when you will most likely run into issues of mixing different brands.