Hi MRK and welcome to the forum.
This depends on your needs and priorities. Your height and weight are not a concern for either one.
The i-9 is like a little pocket rocket. It's loads of fun, handles nicely, travels lighter and smaller than the i-12 and does all the same things. You can stand, take a nap, sail, paddle and pedal.
The i-12, on the other hand, has a huge cargo bay and is ideal for transporting and carrying gear like scuba tanks, passengers, groceries etc. It makes a great rescue vehicle or expedition craft. It's a little faster than the i-9 but compared with your Adventure, you'll find both are quite a bit slower.
They both have a 36" beam and excellent stability, but the i-9 tapers toward the bow and has no forward compartment (not that it is very usable). Both have good power and directional control against the wind and chop though. Both are very stable sailers.
As with all Hobies, I like the large rudder and Turbofins with either, not only for better handling and performance, but both are essential for sailing IMO.
PS Both have quite a bit of weather helm sailing and benefit from raking the mast forward, especially the i-9. Since the inflatable masts are stayed, it's easy to accomplish.