I know, it's been debated over and over, but still, can I ask, please?

I know I want 6x6. I like the square format (I had Lubitel before it was cool, sadly I gave it away) plus my enlarger only goes to 6x6.

I'd mostly shoot portraits, macro and landscape. I know, very different subjects requiring quite equipment. If I had to pick 2, I'd probably leave the landscape out, as 35mm is convenient to carry around, and my back seems to object to heavy load.

Durability is important. Will it last for the next 20, 30 years? Will I find spare parts? A few $100 in price difference today could be meaningless on the long run.

For now I'm opened to TLR and SLR, but I'm leaning towards SLR due to macro requirements. On the other hand, TLR is more convenient. Maybe I'm better off with 2 cameras?

Thanks for any suggestions.