750: Weight wise at 5'7'' is more ideal for the height, new rider, etc.
1100: Added weight, same stance different look and power, but the 750 more caught your eye.
750: New rider is going to adapt to the speed if started out with a 350 and jumped on a 750.
1100: So it's how fast did you learn, you'd like more power, can deal with speed, should have jumped on the big one for the same price.
750: That early a year says most parts will be available. Tin and all, without searching to find out.
1100: The old models should point you away from those years due to age and parts availability. The more worn out, long in the tooth bike(s) to avoid.
750: Has to be stock at all costs. Mods are posts filled [here] with driveability problems and mpg issues; due to a change from stock air cleaners to exhausts; plus the service and aptitude applied to a used bike. You need to concentrate on riding it, not here writing about it getting it to run right.
1100: Same. Has to be stock. Wait for that one as is the other one, if not stock meaning.
750: Think of it like this. If you jumped on an old CB750 back in the day, that was a fast jump from one cc to the next. But now you look at that bike, a current 600cc would leave it in the dust.
1100: Speed is relative, so starting out on either is that you still have to coordinate the hands to clutch and throttle, or you'll flip it going backwards no matter if it's a moped you started out with. It's all about the hands and wrist to make the most powerful bike-run at moped speeds.