Several people on this forum recommended PTGui when I had this same question, and I've been using it happily for a year or so. It's relatively easy to use, and produces good results. I usually export 16-bit TIFF files, and let PTGui work on those, then produce a 16-bit TIFF flat pano which I re-import into Lightroom for final cropping and adjustments.
PTGui works well even on an older iMac with only 8GB of RAM.