I think you just have to stick to types that are around the same size normally (like mice, hamsters, and chipmunks).
Don't get me wrong, I played with them as a child and absolutely loved them. I had pigs and bears back then. And there was a similar line made by sylvanian families that went with a cartoon, called maple town, and I had LOTS of that. I'm still tempted to buy them sometimes, but I have to make myself stick to just playmobil, because if I ever start collecting any other type of toy, I'm sunk. I'll start collecting Calico Critters, legos, duplos, loving family, barbies, madame alexander dolls, polly pocket, littlest pet shop, melissa & doug wooden toys... the list goes on.
That's why I have to make myself be critical of other toy lines.