I've found that butting batting edges together and zig zagging can create a ridge line in your finished quilt. I would also avoid using the tape as it's unclear what the adhesive will do to the cotton fibers of your quilt over time. Plus, if the quilt is minimally quilted, the tape could pull away over time and with repeated washings, causing unwanted lumps in the quilt.
I recommend overlapping your batting pieces 6" or so and cutting an "S" shape through the overlap (or several "S" shapes) if your pieces are long. Remove the excess and butt the curves together, hand stitching with a herringbone stitch. Your splice should be invisible in the finished quilt.
Good luck, whatever you decide to do!