I can give you the perspective of a Model 3 owner with an ID.4 reservation that is due for delivery in the next month or two. The two cars are aimed at slightly different customers.
The Model 3 has amazing performance and handling, is low to the ground and rides and feels like a sports sedan, which is what it is. You feel the bumps due to the low profile tires and firm suspension and there is a fair amount of road and wind noise. Seats are very comfortable, good storage in trunk and good sized frunk. It has advanced driver assistance which continues to improve. Over the air updates are at least once a month with new features being added. Amazing charging network, road trips are very convenient and easy thanks to the network and great charging curve. Plug and charge, no cards or apps needed. Rapid charging attracts a fee which varies by location. Sparse dealer network with 3-4 weeks appt time typical, poor customer service attitude, think entitled, getting someone on the phone next to impossible, they do communicate well via text, you'll never met the mechanic, you probably won't meet your service advisor either. However the mobile service is amazing, though appts can take 4-5 weeks. Shame mobile service can't meet all service needs. Mobile service will met you anywhere to service your car, home, work etc. You get to interact directly with your mechanic.
The ID.4 has average performance, I have held out for the AWD as I found the RWD to be under powered. The ID.4 has good handling and rides very smoothly and quietly, takes the bumps well thanks to the "normal" tire profile. Seats are comfortable, some trims have massage seats (the Tesla doesn't). Storage in trunk is very good, however there is no frunk. Driver assistance is OK, not as good as it needs to be. OTA updates are infrequent. Charging network is sub par, but improving in terms of reliability and number of locations. Charging speed is less than the Model 3 but actually pretty good with a great charging curve. No plug and charge, app required. Free rapid charging for three years with no cap, truly unlimited as far as we know. More service locations than Tesla. I have no experience with their customer service or appt lead times but would expect a traditional dealer service experience.