@MokaPot For tuna I like Ortiz bonito in the oval can. I may be misinformed, but I believe bonito is a small tuna, so it contains less mercury. It's very good quality, and not cheap, but I've discovered that Amazon sells a pack of several cans for a reasonable price--better than I have paid in the past at local gourmet shops.
For sardines I also order from Amazon. Two brands I find to be very good: Santo Amaro, European wild, packed in olive oil, are a pretty good deal if you buy in a 12 tin pack. They are lightly smoked and typically large, three sardines to a can. The other one I like is Matiz, also European wild, a similarly large sardine and more delicate and not smoky, also in olive oil. They are a bit pricier than the Santo Amaro. None of the canned fish are cheap. They are from Spain or Portugal, but I can't remember which. Both have the bone in, which I require. Why toss out one of the best sources of calcium? As for the "wild" part, I believe all sardines are wild caught. They appear to be sustainable, at least on the European coast.
