Matilda would be EW, and the best-armored tank in there as of now. Only the Panzer IV F2 could kill it from the front at any real range.
70mm on the lower hull, 47mm at 67 degrees on the upper hull, 75mm on the turret, 40+25mm on the sides.
Valentine would be less well armored, with 65mm on the turret front, 60mm on the lower hull, 30mm at 68 degrees on the upper hull, but it would also make it into EW with the 6lber, IIRC.
But remember, if we get more tanks in EW, like the Panzer III, Valentine, and M3 stuart, tanks like the T-34 and Panzer IV will become perked.