Match the large table to the sofa, then let the small one be the spare.
Anton Small set is Medium plus Small (70 x 23.5 in with 65 x 21.5 in). Anton Large set is one Large and two Medium tables (100 x 29.5 in with two of 70 x 23.5 in). Leo Medium set is 31.5 in plus 27.5 in rounds; Leo Large set is all three diameters, 37.4, 31.5 and 27.5 in.
If the sofa is a two-seater, start with Anton Small or Leo Medium. If it is a long three-seater and you host, the large set is the one that stretches along the sofa when pulled apart. Height still follows the sofa seat: see the height guide.