This is a tough one. And to find the answer, I am not Googling, or reading reviews, or searching for anecdotal Facebook reports. I am talking to two European top contesters, seeking their first hand, honest, factual opinion. No names (or calls) but you can trust me: they are multiple contest winners, and had both radios in the shack.
Their verdict: probably, just for a tiny bit, the money is on Kenwood TS-890. Regarded as a classic in its price and performance range, it seems that it has that tiny edge only a seasoned contester would notice; something that boils down to the ‘specific flavour of noise in the 37th hour of a two day competition, when the antenna is pointed in a certain direction, while trying to pull a weak West coast station on 80m’. Yes these guys are crazy.
But for you and me, the money should be on IC-7610. Not because I have one to sell you, but because you are most likely looking for an all-around radio, not a contesting radio; a modern transceiver which offers more value for money. The ICOM is not just significantly cheaper, but has two independent receivers (Kenwood only has one).
And in the years to come, there will be more support (remote TX for example) for ICOM than Kenwood.
Let me know when you are ready to upgrade your IC-7300 to IC-7610; I am here to serve you.