RE: Tower Trainer vs Avistar
jentzsch, Looks like you're on the right path to enter this great hobby. Find a local AMA club if possible. There you'll find the help and community of interest to enjoy the hobby. Take advantage of the available resources the club offers. i.e. club trainer aircraft, buddy box, qualified instructors, flight simulators, and on and on.. Club members will want you to succeed as much as you want to! Club swap meets will make equipment available at great prices.
Don't rush. Take your time and choose the right instructor. Many years ago I had "Crash Eddie" help me because the club instructor wasn't at the field yet. Needless to say, Eddie got busy chatting with a flying-buddy while I was airborne and wandered away. My kit-built RCM Basic Trainer did a figure 9, straight-in full throttle. I as heart-broken and left the hobby for a number of years.. I'm back now, older and wiser..
Jimgee