I don't know the new exp formula (it looks very different than it used to), so it's hard to say. But, do you want to grind it up fast, grind it up economically, or level it slowly but surely (and cheaply)?
At that level, dungeon gear from the level 60 roulette dungeons is super economical, but slow. If you don't care about how fast you're going, if you just run those once a day or so and roll on every accessory and GSM-desynthable weapon that drops, you'll definitely level. ~50-55% at first, then as high as 85%-93.5% by the end (see earlier discussion on Valerian equipment and the desynth bonus). You can use excess Law tomes from leveling to desynth Yasha rings, but I'd wait until closer to 170 skill for that. Without the exp formula, I can't really tell you when is mathematically best to start on Yasha, but at 160 skill, you have a 40% chance with Yasha, a 45% chance at 165, 50% at 170, and 60% at 175.
If you want to level it as fast as possible, ignoring any cost, farm Diadem. Desynth the r150 and r180 GSM items instead of turning them in for tokens. With a good farm party, you should be able to get those pretty quickly. You could also try going with friends who are willing to pass on the i150/i180 GSM desynthables, perhaps in exchange for you passing on other items. That'd likely be the fastest, especially with a good zerg farm.
For other classes, notably LTW, ARM, and BSM, I believe it's also totally viable now to grind up from 160 to 170 (and possibly higher?) on the r150 adamantite-containing craftables purchased from the Repository Node in Azys Lla, like the Hunting Belts for LTW. I dunno if Adamantite Nuggets are still 20k, but they were last I checked, making LTW hunting belts pretty revenue-neutral. With lower level items giving more exp, the exp should be worthwhile for a lot longer.
EDIT: But yeah, Law items are great, while you have the Law for them. I don't know that Law farming to get more once you run out is better than just farming i180s in Diadem though, if you don't want to wait until you get more Law incidentally while doing other things.