Don’t know much about coffee (except for drinking a lot of it), but would recommend trying Oklao if you haven’t before - they have multiple branches around Taipei/Taiwan.
I’ve been buying almost all of my coffee from there for about 4 years now, after trying several different places when I first arrived in Taiwan. I usually buy their medium roast and Italian espresso (which is apparently darker than French roast?) for use in a moka pot - 454g bags are NT$300 with buy two get one free*, so NT$200 per bag, which is far cheaper than anywhere else I’ve seen. They have a couple of dozen other (and much more expensive) varieties too.
*I’m not sure whether that’s a regular promotion or the guy in the shop just likes me. They often don’t have the promotional sign outside except during holiday periods, but that’s the price I’ve always paid.