The best tapers are ground on a disk sander. If you have access to one, use it. One of the benchtop 6" disk/4x36" belt sander combos is a very handy tool and does a great job with tapers. I like a "V" groove type guide. AMAW makes a guide block that is grooved for both nock and point tapers. AMAW, KK, 3RA and I all carry them.
The Bearpaw tool is getting some good reports. It looks good, but I haven't used it myself. The pencil sharpener types will work on some of the softwoods like POC, but not on hardwoods or fir.