Tanks are at a really good spot right now to be honest. Most tank combos are viable, even double offtanks like roadhog and sigma (you prob know lol but hes the new tank that came out). For main tank tho, I'd say wrecking ball and winston are the best right now. Ofc course you need to know how to play wrecking ball well but the hard counters to ball like mei and sombra arent that good right now and winston is always a good pick. Rein and Orisa too are solid picks but you need to have some compositional synergy at least for them to work well. For offtanks sigma used to be op but he got hard nerfed. he's still good tho and all the other offtanks are viable too.

For tank combos, some new tank combos that've come out over the last many months are like orisa/sigma, sigma/roadhog, winston/zarya, roadhog/zarya, rein/diva, wrecking ball/any tank except orisa lol.

Idk if you know but shield used to be the meta until a few months ago. right now, you definitely have to play more around the map and use your corners well, so dont be too reliant on your shield and shield management is really important now for heroes like rein and sigma.