it depends on the difficulty level of your ded sites
and the tier level of abyssals that you plan to run
I understand that, since it is the newbies Q/A section, your question is more about low tier abyssal and low level ded sites
but for example
a 10/10 DED in null sec will sometimes give you 300-400M (Some 6/10 can even drop 1B+…) but you will use, for example, a 2B rattlesnake to do them.
A T0 abyssal provides crap whereas Running t5 with a 4B gila and expensive pod will provide several hundreds of millions per hour
For me, it’s easier to get filaments than DED Bookmarks, so even though I like doing DED Sites, Abyssal sites are way easier done in a row. You need no salvager and no travelling, and in most sites you even receive further filaments.
Only the bounties in DED sites are paid in ISK.
For anything else you have to invest further time:
Do you salvage? Do you sell? How well are you prepared? How many drones to replace, where do you get ammo? All this is time and money you have to consider in your equation.
There’s some approximate values players may give you, but I’m pretty sure every player has a different solution, also depending on the ships you use and the experience you already have.
I’d propose to do both, because grinding is getting boring soon. On the other hand, Level 1 is not very profitable, so as soon as you get better, you should level up for better outcome and more fun.