CompGuy

Unless you really hate Quant, you should go to HKS MPP. The reason is because it is better to approach NatSec from an interdisciplinary perspective in my opinion + it is good to have some career flexibility. I know a fair amount of people who have NatSec burn out after years of it non-stop. 
That being said, you are giving up opportunities to work with political risk firms and up close interaction with the Beltway Defense infrastructure. However, there are many different ways to approach defense.

However, if you look at the finalists for the McCain Fellowship for DOD, you have a lot of people outside of DC schools (granted Georgetown is the plurity/majority). Note how some of them did it all the way from the UK!!! 

John S. McCain Strategic Defense Fellows Program - Cohort 1 Finalists (whs.mil)

Extremely struggling between SSP and HKS MPP. Want to get into the NatSec field, but my heart tells me to go HKS (and that it wouldn't preclude me from a NatSec career later down the line). What do you all think?

Public Policy Expert, I hope you were being sarcastic. I'm a second-year MPP at HKS and I can't agree more with the idea that comparing HKS to HLS and HBS is ridiculous. HKS is great at what it does, preparing its students to serve at the highest levels of government and public service. The resources at the school are unbelievable and the opportunities following graduation are amazing. Dozens of alums have gone on to become White House Fellows, work at MBB (and not just dual degrees), became Ambassadors and even heads of state. The median (not mean, median) starting salary for MPPs in the private sector is $122,000. If that doesnt signal the value that the private sector places on K-School grads I dont know what would.
 
Furthermore, the professors are top notch, very accessible, and most are willing to use their contacts to help students get jobs and internships. One professor helped a friend get an internship at the White House last summer.  This also goes for professors across campus. In addition to my HKS professors, I've able to meet with professors in HLS, HBS, the college and they were consistently interested in providing guidance and willing to offer assistance. In the less than two years at the school, I've met and had substantive conversations with four current or former governors, two senators, the head of the World Bank (K-school grad), and many many other dignitaries. These interactions along with those I've had in class have been invaluable to my training.  
 
Many students from HLS, HBS, HMS, the college, HGSE, HDS, etc. cross-register to take HKS classes and vice versa.  As is the case anywhere, students fall along continuum of impressiveness and there is substantial amount of overlap in student quality between schools. In addition, many students have very impressive backgrounds and have been highly successful before coming to HKS. The main difference in applicants is that those who apply to HKS are primarily interested in public service. You should be proud of your accomplishment and know that this will be one of the best experiences of your life. 
 
One final point: I was self-conscious like you were when I first got here but I quickly learned that my concerns were unwarranted.  I will confirm that there is an informal "hierarchy" b/w schools based on the "competitiveness" of entry but you should know that this is just the nature of elitism and exclusion. Harvard attracts a subset of students who define themselves based on the exclusivity of the group they are apart of. Even within HLS or HBS the exclusion doesn't stop it just shifts to different criteria like: are you coming from i-banking or class rank or where you went undergrad. There is a word for people like this: snobs.
 
News Flash: There are snobs at Harvard.  
 
But it's okay! The vast majority of people arent like that. Once you get here you will quickly realize that the snobs are irrelevant to your experience at HKS and to your future opportunities. 

I got aid and there's a paragraph that says I received it.
"Upon the recommendation of the Admissions Committee, I am pleased to approve your admission to the M.A. in Security Studies program, effective with the Fall 2021 Semester. Be sure to print or save a copy of this letter for your future reference.

I am also pleased to inform you that you have been selected to receive a merit-based Graduate School financial aid award. More information about your award and how to accept it is detailed in the financial award letter that will follow."
Then it just talks about putting down a deposit.

I got into SSP too with a "merit scholarship" but it doesn't say how much. Rheana--where'd you find yours?

Aaaah found it--thank you!!

I got into SSP too with a "merit scholarship" but it doesn't say how much. Rheana--where'd you find yours?

Congrats!!! And good luck with those! I'm waiting for SIPA and Stanford:)

Thank you so much for the clarification! All is not lost