I have never really gotten into Cannith Crafting though I maxed out a crafter.

All the posts say to use Cannith gear leveling. Is there like specific ones that are must haves, or is it more like make your own flavor of gear?

Dependent on your build, level, missing stats, ingredients you have or can get. You’re asking a big question and missing a lot of info.

One thing to keep in mind. When they updated Cannith Crafting in 2016 they implemented the Collectibles system into it.

If you never bothered picking the collectibles up it can be a massive pita to farm them for the recipes.

There are two options for leveling CC Crafting:

1)  Go with ONLY CC Crafting.   In this scenario you plan specific levels (Say 4, 8, 12, 16, 20 was an early popular one) where you will have a gear set made   (5, 10, 15, 21 works well) .  You can look at the power curves for the crafting on the wiki and see at what level stats bump up and target those. https://ddowiki.com/page/Cannith_Crafting/table_3b   You can see that for stats, you are getting a new point at 5, 10, 15, and 21.    Another option I like is 4/7/13/18/23.   (this one gets you bumps in both stat and insightful stat simultaneously.  But you miss being able to add the extra effect at ML 10 until level 13)   

Anyways, with this option you are planning to do ALL CC crafting for all slots you can.  As a result you craft the exact same effects on the exact same accessory slots every time.   Your belt is always Con, False Life, Insight Con - For example.   The stats just go up each time.   This ensures that you always have the major effects covered and it makes it super easy to gear.   The negative is that you lose some of the set bonuses and power of named items.   

2)  Go with CC at level 4/5 and then use Slavers at 8, RL gear at 10 and Sharn at 15 and Borderlands at 21 and then use CC to fill in what is missing.   This one probably gives you the most power, but it requires more planning on the CC loot as you have to look at what effects are missing in the named loot at those levels and then what you can craft on the accessory slots that are open.  Use this chart:  https://ddowiki.com/page/Cannith_Crafting/table_1b    With this you will probably be on the 5/10/15/21 type of gear set.

Option 1 requires way more mats because you are crafting every accessory slot.   But it is overall less effort and makes leveling brainless.   You can make a Strength THF Melee set.  An Int Ranged Set, a Cha Caster Set, etc.   And they generally work for a variety of builds.   If you are trying to save mats, you can make your defensive items be the same for each set (like the Con belt I listed above) and then they are universal for all sets.

Hope that helps.      

Don't be shy about asking in guild, channels or forums for collectables to craft.   A lot of players will trade with you or (if they like you) just give you want you need.   The community is strong.

crafted a Level 1 Ring of Feather fall and .... (whatever)
and Lvl 1 Persuasive Goggles of True Sight for my toon that is currently doing TR.  The persuasive helps with UMD

and a couple trinkets for raids.  about the only items I ever crafted, and used.

lvl 1 goggles with true seeing and blindness immunity and a slot for master's gift.