Need expert help

Want to buy a new bike, one of those mid-age dudes that have been out
of it for a long time.

Yesterday, I rode a Trek 7300 and a Cannondale adventure 3 and liked
both of them.

When I got on the Cannondale however, it just "felt right" and I
really liked the way it handled.....had a more durable feel to it and
a more foregiving frame?

What I didn't like about it was the lousy ****ft system.

The Trek's was perfect -- just a click, and you're in gear. The
Cannondale had all these different places where it "maybe" was in gear
etc and noise along with it.

My question is this --

What Cannondale model should I look at that's pretty much an adventure
3 but with a more precise (****mano?) gear ****ft mechanism?

Also, the Cannondale had disc brakes -- out to lunch on that -- what
is the lowdown on disc vs conventional brakes?

Thanks kindly for any help -- I want to get something before the end
of the week.

(Also -- rode a Giant cypress, didn't care for it).