Without more context/information to narrow it down, I'll just spit out a few ideas and hope you'll take a look around the internet for more videos, reviews, and information to guide your purchase:

1. Tissot PRX Quartz
2. Seiko 5 - many styles out there, so take a look around if any might work for you
3. Orient Bambino
4. Orient Mako

The one I think I will actually purchase eventually: Grand Seiko "Sakura" SBGA413

The one that I would really like, and likely never end up buying due to the price, is the Cartier Santos skeleton (one of the many variations).
 

Not at all, I appreciate any information even if it may sound brutal. I figured at the very least it would be a fun physical restoration project for me to undertake at home if the movement is unsalvageable. I paid an amount of money for it which I won't be too unhappy writing off.

Given that the seller claims the only issue is diminished power reserve, I am hoping it can still get by with a simple mainspring replacement.

I'll be sure to update once I have some progress in servicing, repairing, and restoring this piece :) 

Fair enough. If you want my actual opinion (based on my taste/feeling): Sell the Breitling and keep the Omega. Fund the balance for the GS.

If it comes down to that not being an option and there's no way to get the GS without selling both... I'd sell both with a heavy heart.

Everyone has a different approach/philosophy to collecting, but I think some things would apply universally. One of them is to read articles and watch videos of so many watches that you have a wider view of what's out there now - then you'd be better-equipped to narrow down what you'd like next. Too many times the "next watch on the list" got bumped or removed because I learned of the existence of something that fit my wants better.

Also, if there isn't something that just speaks out to you (don't try to "force" yourself into liking something, it should speak to you first), just wait for something to come up. New watches are coming out all the time.

It really depends on how much you love the watches you own now. I'd personally do a lot for a Spring Drive GS.

I can't make the decision for you but my advice is to sleep on it a while. You can always get the GS any time (well, sort of) but once you sell what you own, that's likely the end of it forever. My mum always did say "think 10 times before buying anything", and I generally spend weeks online just watching videos of what I want and comparing against something else (in your case this is probably moot, because I'm sure you want the GS and it is a good choice); but you could watch videos of your own watches to see if there are any points of appreciation you might have missed, and perhaps would prefer to buy the GS and keep one or both of your old watches. 

Found you some information my man. It's not much, but if you have any specific information you'd like, I'd be happy to help.

https://mybulova.com/watches/1946-cadet-9023

I think it's a beautiful vintage watch that would not look out of place even today.