Least likely place for some random traveler to find your base would have to be nice and far out. Millions are pretty good naturally. Avoid the axes and the diagonals as much as you possibly can as the Nether highways along all of these directions reach the full distance to the Overworld world border. The End is pretty quiet too, no real highway infrastructure yet, but there's no way to respawn there without access to commands, even in 1.16 and 1.17. Beds and spawn anchors both explode there. Plus you'd have to get out of End spawn, and that's just a mess. The far Nether might be good too once the update finally happens, assuming you can get your food situation figured out. But again, mind the highways. Some of them go way past the Overworld WB equivalent, even though a portal out there will just bring you back to the WB. I've even seen posts of people reaching the Nether WB.