Actually internal frames predate externals and the early forerunners of both types that were in use about 100 years ago were pretty bad compared to those that came later. In the 1950s Dick Kelty boosted modern backpacking with his development of a great external frame. I would still be using mine if it hadn't been stolen.

Really good external frames came along in the 1970s (North Face et al). Built and packed right, they carry just as well and are easier to use in rough brush and rocky situations, hence are generally more versatile. I still use an external frame for really weird loads like fossil mammoth parts and the like.

Use whichever holds the load you plan to carry and that fits you best. Fit trumps everything.

PS. If you will have the need to stow your gear in a plane, helicopter, or boat, the internal frame pack rules...