But I think limiting yourself to Speyside is foolish. The fact that you do this makes me assume you've tried single malts from other areas, and I also presume that you didn't just try one once and jump to the conclusion that everything not Speyside sucks. So maybe you don't need this advice, but I'll give it anyway.
I'm a big Speyside fan, and most of the time I buy a reasonably expensive bottle that's where it's from, but there are some great bottles from other areas, in particular (for me at least) Islay and the Islands. Talisker for example is like no whisky I've ever drunk, but is pretty fantastic. Laphroaig and Ardbeg are two Islays that have some really nice releases, and even Bowmore, despite being a brand best known for cheap and average bottles in supermarkets, have a few decent ones.
Oh, and even outside Scotland you might be surprised. Ever tried Yamazaki from Japan?