What is a good party that includes an Onion Knight in Final Fantasy III?

I'm getting ahead of myself because I just got my second set of jobs but I already Have Onion Knight. & right now I have this party:

Luneth - Onion Knight
Arc - White Mage
Refia - Geomancer
Ingus - Knight

I was wondering, later on in the game once I've gotten all the jobs available, what would be the best combination? If I include Onion Knight, I was thinking Onion Knight, Sage, Ninja, Dark Knight. And without Onion knight i was thinking Dragoon, Sage, Ninja, Dark Knight. Which is better? and is there anything that I should change or is wrong with my theoretical teams? Oh and another alternative is to have all of them Onion Knights but idk, i'm really hesitant about that. SO yeah let me know, thanks a bunch in advance!

Well as of now my party @ lvl 35 is :

Luneth - Dragoon job lvl 33/ Onion Knight job lvl 92
Arc - White Mage job lvl 32/Thief job lvl 82
Refia - Geomancer job lvl 47/ White Mage job lvl 11
Ingus - Dark Knight job vl 22

the only reason i changed Arc into a thief is because I'm trying to get Gungnir from Odin. Which I do, but then i keep dying from Zantetsuken -_-. Oh and right after I do this and get my final set of jobs. I'm going to change Arc into a Sage and Refia into a Ninja. Problem is, I want everyone to be able to have HP 9999, sooo... i understand the whole black belt job & high vitality but, how do I go about this? should I train all my characters to lvl 99 or whatever to get to HP 9999 and then continue with the game because i don't want to finish the game with lvl 60 characters just to findout that i can longer achieve HP 9999. so any suggestions. please and thank you

Okay i see. And then my other dilemma is that i'm kinda OCD with wat jobs my characters' jobs are based on looks like the fact that Luneth does not i any way suit a mage or a scholar look. Which is why my final set up was going to be Dragoon, Ninja, Sage, and Dark Knight. But then I was thinking Luneth has like grayish hair and his name kinda goes with Luna like the moon soo would he look better as a Dark Knight and Ingus as a Dragoon? Which if that's the case, it would be kind of frustrating cause i already started leveling up their job levels. Also Is it better to have a Devout than a Sage? I understandthe whole Sage doesn't have a lot of MP but i was thinking by the time I'd reach high levels, does that really matter? I'd think that the damage was so insignificant or not signoificant enough for me to be spamming heal spells & plus I want a sage because YO i spent a lot of money on getting all the magic that i'd like to use variety like summons/black/white magic. cause it pisses me off for the fact that i really only use white mages/devouts to guard or cast cura/curaga or raise/protect while the other white magic just sits there. & that's it lol. Tell me what you think, I know, it's a lot haha.

What ever u do, DO NOT EQUIP ONION KNIGHT TILL LEVEL 93 or more. If u noticed, when at level (for example) 64 they have the LOWEST STATS OF ALL!!! They have like 14 or 15 in all of them. But once the reach Level 93, all stats SKYROCKET going from stats of 15 to stats of like 37 to 99 in all stats. Best not use onion knight till 99 or 93-99. Sage is good, as it summons and uses both Black and White magic, all though has less. Have him with high Intellect or Mind and use a Level 8 spell, and he is good. Ninja is good, for high attack weapons, such as shurikens and I never (rarely EVER) use knight. I find no use of it, sadly, as to defend allies at low hp (Yellow Numbers), u need MASSIVE defense, ESPECIALLY for the later parts, as they hit harder.If he has super high health, and barely gets hit (1 - 400 [for later parts, with about 125 or 150ish defense, He gets hit with about 200]) then use knight, I found absolutely NO use of Knight whatsoever, so do not take my opinion in knightliness

Please don't use your Onion Knight this early - the low vitality means when you level up you will not get max HP gain. After a few levels, you will notice your onion knight is way below the HP of others!! This could hurt you later.
Recommened: when you do job level grinding, slide your onion knight into the party to level up the job, but don't character level up with the job.
But hold off using your onion knight for dungeons and progressing in the game until much later!