Hopefully Metallurgy will rebalance some of the metals and alloys soon. There are some strictly and obviously best choices that render almost everything else useless. Almost from the moment you get your smeltery, Damascus Steel is available, and makes a very solid choice for a long time, getting you from an iron-equivalent all the way into the nether for your first cobalt. Making advanced tools out of DSteel early on is a similarly great choice. From there, you'll move to kelendrite and will probably be able to stick to vulcanite for a very long time (unless you come across a lot of sanguinite, but I'd save that for a hammer). Eventually you'll make the jump to tartarite.
Aside from armor, there's very little to no advantage I'VE found to taking any other route. The ores, at least using the global configs, are located in about that order of difficulty to find, and since it only takes 1 ingot to make a very passible pickaxe, you can jump through the tech tree very quickly.
Everything else is just taking up space right now. IMO, the various steels need significant rebalancing (even though that probably means that DSteel would be nerfed), and every metal needs some kind of modifier to make the decisions of what and how to make your tools more interesting.