Once your start looking, just hold on to your credit card. There are so many to choose from. Like Kathy, I've purchased from several different vendors and like the Handiquilter templates and Jamie Wallen's at
http://www.quiltersapothecary.com the best. The ones that are most useful have quarter inch, 45 degree and 60 degree markings etched on them. These sources have videos on how to use the templates.
http://www.handiquilter.com/shop/product/ruler-handi-versatool/ is a great place to start for not only ditch quilting, but for all kinds of designs.
I do not find the Line Tamer easy to use.
I have one arc from a company that has little holder posts coming off the template on the perpendicular. They break off. Jamie's are easy to hold and his latest ones add more angles.
Elmer's Dots (sold by Handiquilter but probably available elsewhere) are great because they help the ruler grip the fabric without overly doing so, and unlike the sandpaper dots which I find ridiculously expensive, there are a lot of dots in the applicator.
Kimmy Brunner has a Craftsy course on Precision Quilting using Templates which may be on 50% sale right now. If not, just wait, it will be. Don't be afraid to watch long-arm videos on using templates. All of the information is applicable, just some of it is a little different.
The more I use rulers, the more I like them.
Did you get the overlay for your table? This is a huge help keeping the templates level.
Congratulations on your new machine. I'm sure you will be in love, if you are not already.