Everyone goes on about rye flour like it's magic, but my starter took off with plain all-purpose. I tried rye once and it made the starter too sour too fast, ruined a whole batch of bread. All-purpose is cheaper and you can find it anywhere, no special trips to the store. My loaves rise just as high with the simple stuff. Why complicate things with fancy flours?
My starter's been going strong for years on half whole wheat, half all-purpose. It's a good middle ground for flavor and reliability, kind of like what @kellyw44 said about keeping things simple. I just find the mix gives it a bit more character without going overboard.