I had a root canal years ago and, honestly, it was relatively painless. Mine was a premolar, and the pain was the next day from holding my jaw open for so long -- it would probably be worse for a molar, in your case. But the actual root canal itself involved liberal use of novocaine, and didn't hurt at all.
For reasons unrelated to the root canal, a couple years later I had the tooth pulled, a bone graft, and an implant. Those procedures were more painful than the root canal, the recovery was worse. But now, the implant is several years old and fine. Never any pain or problem from it.
I can't advise you about the root canal or implant, just sharing my experience with both.