The consensus seems to be that Monero is a little better in terms of privacy, but Grin is pretty good. Grin is limited to 10-20 TPS, tops. Monero is theoretically capable of 1,700 TPS. Grin has amazing scaling in terms of blockchain size, but that's not very important IMO.
Mind expanding on the bolded? As this is the bit that seems to be the hardest criticism of Monero. Are you thinking layer 2 is the answer? Similar to BTC? Moores law? Etc?