Culling Your Herd

So I'm now level 6 and would love to really start breeding and furthering my lines.

My goal is to strictly breed Appaloosas in each specialty, as well as bettering conformation as I go.

How do you guys cull your foals? Compare filly + dam, and colt + sire together? Genes don't bother me, as long as I can keep Andromeda's rabicano to a minimum and eventually cull it out, I'm happy.
I'm having to put together a spreadsheet to do this so I can follow my progress.

As an example, I bred my dressage-specialized Appies and this is the outcome:

Andromeda's Flame x Titanium produced this: Foal
Umbra x Dustdevil produced this: Foal
Sakura x Dustdevil produced this: Foal

In Dustdevil's case, both his foals are colts, so would you guys compare both foals and see which one is better?

Any help is appreciated! Thank you! :D

Anyone able to help? Still a little stumped.

So everyone does it differently!! For me, my process has evolved over time. I have a spreadsheet where I list: 

Name - Sire - Dam - Grandsire - Granddam - Grandsire - Granddam - Coat Color - Genotype - NSS - Even/Odd/Etc. NSS - Other Related Horses (Where I list every horse visible in pedigree, to prevent inbreeding)

Then I match based on pedigree (ensuring no inbreeding) and NSS (prioritizing pairs with mismatching Even/Odd NSS), and breed 3-4 foals per pair. 

Now comes the culling! For me, I keep in mind the things I care most about in my lines. I want low NSS, so if one of the 3-4 foals has the lowest NSS, that's a keeper. Next comes genotype, confo, stats, etc. I pick the top foal from each of my breeding pairs and sell/donate the rest. If I'm being particular, I may keep the top two if they have different even-odd NSS, to wait and see if I can find an eligible mate from another breeding pair's offspring, and sell whichever of the foals has more matching NSS. 

It's up to your priorities, really.
Personally, I usually breed 3-4x, and I keep only one foal per pair (as I want to prevent in- or linebreeding). I cull or sell the other foals.

As I breed for conformation and NSS, I compare the foals of the same pair. I try to choose the foal with better overall average conformation than the average of its parents (as the improvement of conformation is the slowest and hardest).
Second factor is NSS (as it is easier to lower), if I have two foals with very similar overall average conformation, I choose the one with lower NSS. 

Sometimes, I choose foals with worse conformation if their NSS lowered a ton, but most of the time I aim for conformation in the first round.

I'm still in the first few gens with my herds so it's hard to tell if my approach really works, but on the basis of my Excel sheet, the generations slowly improve conformation and lower NSS at the same time - with NSS being more visible.