There are numerous threads comparing average damage of Magic Missile to Chromatic Orb showing the below.

Raw average damage comparison: 

Level   Magic Missile  Chromatic Orb
1       10.5           13.5
2       14             18
3       17.5           22.5
4       21             27
5       24.5           31.5

Adjusted for flat 60% hit rate for Chromatic Orb: 

Level   Magic Missile  Chromatic Orb
1       10.5           8.1
2       14             10.8
3       17.5           13.5
4       21             16.2
5       24.5           18.9

This may be true for Sorcerers, but Wizards benefiting from a Familiar is a glaring oversight. A Familiar using the 'Help' action on it's turn will grant the Wizard advantage on every round.

If we use a flat hit rate of 84%, the table is as follows:

Level   Magic Missile  Chromatic Orb
1       10.5           11.3
2       14             15.1
3       17.5           18.9
4       21             22.7
5       24.5           26.5

This has me leaning to Chromatic Orb, as Magic Missle feels a bit lackluster in combat alongside other classes.

I've borrowed these figures from posters who are much more mathematically inclined than I, so let me know if anything looks off.

I'm not going to question your math, it looks fine. I do question whether putting a familiar in harm's way is worth ~1 point of damage. There's an opportunity cost to using your familiar for that extra damage. That familiar could be helping another player, like your rogue, to land their hit or keeping an eye out for hidden foes. This could significantly increase the average damage of the party rather than giving you a minor boost in damage.

That being said, do what your character would do and what makes the game more fun.

This is a very good point given that martial party members don't have an auto-hitting equivalent to magic missile. Thanks for your input!

Also important to note that you don't have to make an attack roll for Magic Missile.  You declare it, and unless the target(s) have Shield or an item with specified Magic Missile immunity, they take the damage.  With Chromatic Orb, you have to successfully hit them with a ranged spell attack.

And while it may not matter to your particular table, the components of the spells are also relevant here.  Magic Missile has no Material component, so as long as your hands are free and you can speak, you can cast Magic Missile.  Chromatic Orb has the Material component of a diamond worth 50 gp or more.  In the early game, that is extremely prohibitive for any caster (RAW, an Arcane Focus cannot replace a component with a listed cost, or one that is consumed -- CO's diamond has a cost).  Late game the gold cost is largely irrelevant, but you still need to have the component to cast the spell.  If you have been imprisoned, and your possessions taken, you can't cast Chromatic Orb.  But you can still cast Magic Missile.

Quote from drag0n_77 >>

Also important to note that you don't have to make an attack roll for Magic Missile.  You declare it, and unless the target(s) have Shield or an item with specified Magic Missile immunity, they take the damage.  With Chromatic Orb, you have to successfully hit them with a ranged spell attack.

That's the big point. While the expected damage for chromatic orb might be highter, and its maximum damage certainly higher (on a critical hit), its minimum damage is zero.

Chromatic orb does 0 to 48 damage.
Magic missile does 6 to 15 damage.

Additionally, magic missile does force damage, the least resisted type of damage.

One advantage of chromatic orb is that you can pick the element type at casting time. It is a very flexible spell.

Don’t worry about your familiar getting hit, just change it to a creature with flyby like an Owl and it can stay out of harms way and not provoke opportunity attacks. 
Advantage is worth a lot. Mathematically it’s like adding +4 to a d20 roll (and disadvantage is like -4). Just keep in mind that the extreme low or high end rolls on a d20 (like 1-3 and 19-20) advantage and disadvantage make a lot less difference - equivalent to ±1 or ±2. But for midrange rolls - ones you need to roll an 8-14 on a d20 to beat, before adding your modifiers - it’s equivalent to ±5. 
Your math is correct but this means that if you have to roll above a 14 to hit the target with Chromatic Orb the benefit from advantage starts to go down. Simply put: the harder something is to hit, the better magic missile is (which we all knew anyways because it auto hits).

The game designers did a pretty good job of balancing out the spells. Chromatic Orb used well and with advantage is fantastic and powerful. it’s a risk vs reward Spell opposed to magic missile just auto damage. Ultimately play what feels the most fun for you and don’t worry too much about optimizing damage. Just optimize your tactics and play whatever inspires you. The spells are balanced well enough that neither is superior to the other, just slightly more useful in different circumstances. 

I'm looking forward to putting my Dragon Breath Owl into play next session!

I found this advantage chart while doing my number crunching, but in the end just used the flat % chance to hit from here. Thanks for the reminder on the curve as I only memorised the +3.3 average figure. It would definitely alter the numbers in the long run.

Quote from Arliya >>

I'm looking forward to putting my Dragon Breath Owl into play next session!

I found this advantage chart while doing my number crunching, but in the end just used the flat % chance to hit from here. Thanks for the reminder on the curve as I only memorised the +3.3 average figure. It would definitely alter the numbers in the long run.

 Ha dragon breath owl sounds hilarious. That chart is bang on and a good reference. Nice find. Although it looks like they didn’t account for the automatic miss on a roll of one. The real number would be more like +3.825. That’s why we round to +4 approx. And besides the diminishing returns on advantage really only matter on the extreme end for rolls. So like if you need to roll an 18 or higher just to hit. I find it’s generally a non-issue for most play.

Good post.