Those three skills do not go together well.
for which skills go together.
My standing advice to new players is to not do a crafting skill on their first character...at least not right away; instead take two gathering skills (of the three: archeology, scavenging, and bioanalysis), and slicing. You can either sell what you gather on the GTN - usually for good credits, or you can stockpile materials for when you do decide to take up a crafting crew skill.
If you insist on taking a crafting skill, avoid armormech and armstech because those skills provide you with nothing your jedi knight can potentially use.
Synthweaving is the best min/max option because you can have two companions with +5 crit chance to synthweaving (Kira, and your ship droid [although you'll have to spend 100k credits to get any bonuses on your ship droid]). Synthweaving does craft heavy armor that a Jedi Knight can use, armormech does not.
Biochem is close behind as another companion gets +5 crit to biochem, but there is only +efficiency to biochem for the ship droid (again 100k credits)
Cybertech is never a bad choice because of all the moddable armor out there. Cybertech makes Armorings and Mods that fit into that gear.
And Artifice is not bad either because it can provide hilts and color crystals for lightsabers, and enhancements for all moddable gear. Not to mention dye modules to color your gear.