Tried a lot of grills but the Matador grill plate from bunnings [240 x 480 @ $35.05] beats all for great burgers.
Bunnings previously also had a 400 x 480 but not shown any more, it is available on Ebay for around $80, should fit most BBQ's
Grill has a fair bit of flat surface but as well ample slots to get a good char and drain channels for fat.
Bought both the 240 and the 400 and provides a great surface area if just cooking for 2 as in the pictures or both grills to feed the gang.
Sure beats beef patties swimming in grease on a hot plate