I'm very grateful to both of you for informing me so well and in so much detail

I understand many game aspects much better now. From my point of view, I would definitely prefer APA rules, though I understand those who are not so eager to use them. However, the way I usually play 8ball in my area is different from both BCA and APA variant. It's a little complex, so let me describe it step by step.
Basics
We play either standalone games or matches which can consist of any number of games. If the number is even, there's a possibility of a draw (obviously).
We play either 1v1 or in teams. The number of players on both sides isn't determined (for example 2v1, 1v3, 2v3) but it's most often 2v2.
We try to keep teams balanced by choosing the players according to their skill level and ability (for example, a very skilled one and a low-skilled one vs two mid-range players). However, we always play for fun so we shift teams all the time and try out all combinations :grin:
Break
Before the start, we decide which side breaks first. Breaking then changes between the two sides every following game.
The player can place the cue ball anywhere behind the break line. He gets what he pockets on the break. If he sinks both stripes and solids, his color is the one which dropped first.
If nothing dropped, the next player gets the shot and can shoot anything until the first colored ball is pocketed.
In case of Scratch, the player gets the color he pocketed, but the CB is returned on the headspot and the next player gets the shot. When shooting from the headspot, you're only allowed to hit the rails and balls below an imaginary line which splits the table in two (from the center of one side pocket to the other, I hope you got this xD). This applies every time a Scratch occurs.
If you pocket the 8 ball on the break you win, but if any other ball goes in along with it (including the CB), it's a loss. We still have arguements about this rule...
Game
You have to pocket at least one of your balls every shot to continue playing. It doesn't matter if you sink your opponent's balls in the same move.
You have to drop all of your balls and then you need to sink the 8 in the pocket where you dropped your last ball (the marked pocket).
If you pocket the 8 in the wrong pocket you lose.
If at any time during the match you hit the 8 ball with the CB directly (before touching other rails or balls), you lose. This obviously doesn't apply after you sink your last ball :grin:
If you touch your opponent's balls directly you lose the turn and the opponent can choose to either sink the ball you hit or keep it on the table (for strategic reasons).
There's no requirements for touching the rails or any balls during any shot. There are no penalties, no BiH, you only lose your turn if you don't sink your balls. However, we don't scratch intentionally (the rules would allow it, but we kinda came to an agreement ). Well, at least some of us don't...
And then there's this special rule some players use and some don't but I personally like it. When the 8 comes very close to an unmarked pocket which makes it practically impossible to send it away without dropping it, we place it on the head rail behind the headspot.
Now, every other player likes to change a rule or two, but I described the core of the game. I don't know if you're familiar with such rules for 8ball in the US, but that's how we play in my little part of Europe

Hope you like it!