I do realize the BBB method is still used in other sources, but am just curious as to the "main" source. Does that make sense? Sorry if I seem ignorant, I am. I am trying to learn still and am curious about what others are doing for the main source of chlorine.
You have a good head on your shoulders for doing the research before you purchase your pool. You will be able to decide and learn about your pool chemistry before your purchase. take a look at the equipment sections of this forum to help with maint issues on different styles of pools. They all have there plus and minus. The people here are willing to help you and they don't mind the questions. so ask away we understand, that is what the forum is about.
I'd have to vote for the SWCG system. However, here's another twist. My pool is open year-round so when the temps drop below the mid-50's consistently, I turn off the generator and go to strictly BBB. Last winter, an atypical cold one, that amounted to 5 full months of BBB. I waited until the temps were consistently near 60 before turning the SWCG back on.
The method of chlorination to use depends on part on the suface of your pool, the type of filter you use, and your geographic location. For example, stabilzied chlorine (trichlor/dichlor) works well in areas with a short swim season that winterize pools, especially with sand filter, since the CYA is constanly being diluted but are a disaster with cartridge filters or non backwash DE filters in areas with extended swim seasons that keep the pools open year round.
Trichlor is a good choice on NEW plaster pools because it helps keep the pH in line as the plaster cures but you do need to keep a watch on the CYA levels, particularly if you don't have a sand filter.
Metals (call them minerals or ions if it makes you feel better but they are metals--copper, silver, and/or zinc) are NOT primary sanitizers but only supplimental ones that MUST be used with a residual sanitizer (usually chlorine). In theory they will allow you to use a lower FC level but in actual practice this is not advisable.
The type of chlorination that is used might change depending on the time of year, the age of the pool, and also if any equipment is changed. There are basically only 2 types of clorine--stabilized and unstabilized, and which one is a better choice depends on the factors I listed above.