You can stay on top of the 1.5L dilution issue by using Top Tier gas only, using high quality oil (like Amsoil Signature) and changing it every 5K or whenever it gets high or smells, and making sure valves/injectors are always clean. This is a fairly common issue with any direct-injection engine, especially in cold climates.

Also consider the fact that 1.5L is turbocharged, and no one really knows how well that will hold up at high mileage in the Civic yet. I think they use a Mitsubishi turbocharger (MHI TD025?), which has a good reputation for durable turbos. I wouldn’t worry too much as long as you maintain the car well.

You can always go with the 2.0L NA engine, which is available on 2016-2018 LX and EX models, and 2019 LX and Sport models. (The Si and all trims of Hatchbacks have turbocharged GDI engines.) This 2.0L NA is a proven K20-series engine, but it has slightly less HP, noticeably less torque, about 1 more second 0-60, and gets like 1-2 less MPG (but potentially more consistent/predictable MPG, especially at higher speed.)

I’m personally going with the 2019 Sport sedan because I live in northeast US and want to keep it for 300K+ miles.