OP: How far are you able to throw? This will help suggestions be more accurate based on your power level.
If you want to stay innova a mako would be a good choice.
The tangent, like others have said, could work very well. Like the Comet, I feel the tangent is truly neutral. The only time I see turn from it is throwing chest high 90%+ power or anhyzer. For me, it's closer to a mako then comet. Super easy to throw straight. It just wants to stay on the line you throw.
The warship from Westside is also great for throwing straight easy. For me its like a Buzzz with less fade and a little less HSS. Really smitten with the glide this disc has. I am curious as to what will happen with heavy wind.
Either way you go there are tons of options. It wouldn't be a bad idea to pick up a Buzzz or Roc if anything to provide a baseline for future disc comparisons.