I'd toss a couple quick observations to look into just based on web site research only.
1. The new Rize X has a torque sensor -
Aventon does not. No new Rize models have been delivered and reported on yet, so can't confirm it's performance, but I have a Rize X and an RX Pro (with Torque sensor), and the torque sensor is very nice once dialed in.
2. The new Rize X has a 52V battery - Aventon 48V. This won't necessarily change the range significantly - if at all - but it will mean the Rize can perform at full power for longer.
3. The Rize includes the rear rack. Aventon is an option. The integrated front rack (again option) look neat on the Aventon though.
4. Weight is so close, that 2lbs is insignificant, and a rear rack would almost equalize that by itself.
5. The rear light on the Aventon seems small and limited. A set of panniers would easily block it, and it's quite low and offset, so visibility might be more restricted than a typical rear rack mount.
6. The new Rize has brake integrated rear light meaning it comes on with brake. Aventon does not.
7. The Rize includes an adjustable handlebar stem - Aventon is fixed.
8. Drivetrain components are very similar, but the Aventon seems to be one small step up the ladder (Acera on Aventon vs Alivio on the Rize).
None of these are deal breakers by any means, but it seems like the new model Rize X is still a pretty good value for the money. Since it's a new design year though, it's all unproven until it's in the hands of people who can give fair feedback.