SeaBlock VS Factorissimo2

I would recommend starting with Krastorio 2 or Industrial Revolution 3. Krastorio (the original) isn't currently being developed, and afaik K2 is better. Industrial Revolution 1 and 2 are unavalaiable. Both are great starter overhaul mods, and can be a good way to get into modded games. Some other mods that you might want to check out are MSI II, Warptorio, Seablock, and Space Exploration. MSI II is an expansion of the base game, making it a bit more linear and storylined. Warptorio is vanilla factorio with a fun twist of base management. Seablock and Space Exploration are bigger overhauls, and aren't usually ones that beginners to mods jump into. But they're not the worst out there, and many people have played and enjoy them. I think you would like IR3 and SE the most, based on your preferences. But be sure to search around the factorio mod site to see what peaks your interest.

So - you finally decided to start a seablock run after playing around in vanilla factorio (or maybe some space exploration / K2 / AE / etc). You load up a new install of factorio, search the mod listing for seablock... and find 2 options: seablock, and seablock pack. Perhaps going by the latest update (seablock), or by just the name, you decide to select seablock - start the game... and its not quite the same as you expect (or perhaps you post some screenshots of your starter base online and notice all the comments of 'you got the wrong modpack!'). So let me clarify for you!

Found and fixed for the next version.

You should grab the seablock pack from the mod directory instead of just the seablock mod. It will have all the needed dependencies to get you started, to which you can add whatever QOL mods you wish.

Second this - dont just look at the base 'seablock' mod, but also grab the 'seablock pack' mod. The second provides all the necessary mods you should play with (including QOL mods like helmod and FNEI).

I also recommend the mod Factorissimo2 (official mod portal link). Basically you can move sections of your factory inside these buildings TARDIS-style.

If I understand that program correctly it's closer to how you use functions/subroutines in programming. In there you have a clear and enforced boundary for inputs and outputs, boundaries that don't exist in base Factorio. The only thing close to that would be the Factorissimo2 mod.

The fact that all factorissimo buildings share a surface means that the OP is using the factorissimo 2 notnotmelon fork mod (with single surface option enabled) instead of the original factorissimo (2) mod. This is the correct thing to do - the notnotmelon fork is a much more up-to-date version that has been heavily optimized and is thus not a huge weight on UPS.

Factorissimo2

Factorissimo 2: The updated mod for current version of factorio. Also features quite terrible UPS - probably fine if you want to use like 10-100 buildings tops, but dont even try going for anything close to mega-base.

As a side note - are you using the original factorissimo2 mod or the notnotmelon fork? If you arent on the fork version and you arent too far into the run I would recommend switching to the fork - it is much better in terms of UPS and is more or less required if you are going to aim for a mega-base size factory-in-a-box build.

Factorissimo 2 - adds a building that you can walk inside that is larger on the inside, effectively allowing you to build an entire factory inside a smaller building. UPS heavy due to may additional entities it needs to add to have everything work out, plus all the item transfers (belts in/out) are done via scrips (which as I mentioned is incredibly inefficient). Can completely tank your UPS into the single digits if you make heavy use of this mod.

The factory buildings are provided by the Factorissimo2 mod. You place them down, build your factory inside, and send resources by pipe or belt through the connection points. I'm using the Factorissimo2 Playthrough mod, in which you start in a tier-3 factory building and cannot escape. As an additional challenge, I decided to use only tier-1 factory buildings, which are not that big and have just 16 connection points. Since the buildings are small, I needed to use four levels of recursion and many factory buildings -- 59 buildings in all!