Most every Sigma Art lens has been a revelation for some reason or another, especially...
18-35/1.8 - first f/1.8 zoom for APS-C;
24-35/2 - first f/2 zoom for FF;
50-100/1.8 - first f/1.8 telezoom zoom for APS-C;
20/1.4, 14/1.8 - first of a kind in their respective FLs;
Apart from these lenses with unique stats, we have some other contenders:
85/1.4 - the first lens to give the 5DSR a run for its money in a Photozone test;
50/1.4 - the beacon for every modern 50, one that destroyed most lenses in its class and did not break the bank;
et cetera...
18-35/1.8 - first f/1.8 zoom for APS-C;
24-35/2 - first f/2 zoom for FF;
50-100/1.8 - first f/1.8 telezoom zoom for APS-C;
20/1.4, 14/1.8 - first of a kind in their respective FLs;
Apart from these lenses with unique stats, we have some other contenders:
85/1.4 - the first lens to give the 5DSR a run for its money in a Photozone test;
50/1.4 - the beacon for every modern 50, one that destroyed most lenses in its class and did not break the bank;
et cetera...