Have only scanned other replies briefly. Here's my tuppence:
1. DBX over AspX purely because the buy-back won't kill you. If you've been playing just a handful of days, you'll be wanting to spend some time learning how to jump, fly, fight, die. And yes, learning how to die is significant, so keeping your buyback low is important.
2. People will have a lot to say about AspX super-magic abilities, but they'll be less forthcoming about how long they spent grinding engineers and rolling those goldens to get those lovely numbers. It's a nice ship, but a DBX is much easier and cheaper to fit out in a way that gets you functionality without too much grind.
3. DBX will allow you to keep hold of your little eagle, which is a decent enough ride to learn to fight in. Stripping and selling ships is one way to go, sure, but if you rely on a single vessel - selling the last to pay for the next - you're in real danger of not quite being able to make that insurance payment that one time and then returning to a 'winder. That's not fun.
4. You will, eventually, get an AspX. There's no hurry. Learn what you want from a ship, what optionals and things you like to have, what sort of stuff you find most fun (I get a huge kick out of killing numpties who interdict me while I'm on a mission binge, eg), and then build a ship around that. A hundred people can give you a hundred different builds and not one of them will be perfect for you until you know what you need your ship to do.
Plus, you'll be coming into an all-rounder from a combat ship. Whatever you buy, it's going to feel like you're flying a fart-filled paper bag at first.
5. DBX is seriously underrated as a very cheap all-rounder that can be refitted to almost any purpose. The nice thing about it being so cheap is that you can play around and around with your outfitting without it ever costing a fortune. And you can keep all those extra bits in storage and return to them if you want to try something new.
6. Re fuel scoops: KGB FOAM are the scoopable star types. Heat management isn't so bad, and you can plot a route in your galaxy map to keep you jumping to scoopable systems as needed. If you want to compromise cargo space for scooping an extra 8 seconds before your tank is refilled, by all means, get the giant scoop. Or... get a DBX and buy BOTH scoops and play around.
7. Final thought: no point getting anywhere near an AspX until you have some engineers unlocked. To get them sorted, you'll need both an all-rounder and some kind of bang-bang shooty vessel. DBX and Eagle will serve you well, and also offer you cheap parts to sod around with when you start rolling your blueprints.
But, you know what, beyond all that... welcome to the game! Fly safe, stay crazy. And ignore anything the A-Team tell you - they're all drunks and fools.
"Drink fast, die young"
"You may ask who was wearing the bow tie; me or the shark. The answer is: YES."