Hey christov11, all these choices can get overwhelming (but fun), doesn't it?
I can't speak of the magneto since I do not have one, but when I find something that piques my interest, I look for reviews on youtube.
It helps narrowing down my choices. As for your tank selection, since you already own Aerotank mini, I would recommend the mega. That way you don't have to stock different coils. If stocking different coils is not issue and you want to try nautilus go for it. I heard great things about them, and some claim that it is better than kanger line.
Generally online stores are cheaper than B&Ms, and VT store is a good place as any out there. I have not ordered from them yet since the pickings were slim when I first started shopping for vape gear.
Have fun with your shopping adventure.