Clearly the best way is to butt weld the repair panels, it is much easier to bump the metal back into shape than with a lap weld. I have seen many good repair jobs done with a flanging tool lap weld. You do not see many butt weld repairs as they are almost undetectable.
I once worked with a guy that would not use any metal other than what came from that year make car/truck he would cut repair panels out of hoods roofs to make the panels then cut thin strips from the same for filler and TIG weld them in. I thought he was nuts but he was very skilled at making panels.
What you do depends on what you want when you are done.
Is doing the work some thing you want to learn or just a chore to get to the end?
How much can you spend on the project? I do work for people that do restorations by check book.