For all around automotive use it's hard to beat the IR-301, good price to performance, but not made in the USA. I can't think of any of the automotive grade grinders that are made in the USA, even the ones that are marked that way are mostly offshore mechanism in a US housing.
What is your use for the tool? If it's just typical automotive use, I would recommend the IR-301. If your using it all day then step up to an industrial tool, I would recommend something from TC Service, good USA stuff.
Why do you need a geared tool? Geared tools have less power (for the same motor), much less reliability/life and cost much more than straight tools. If you can get away with a pistol grip or straight grinder you will be $$$ and performance ahead.
What wheels are you planing to run on it? IMHO the standard 90* grinders are good to 2" wheels, 3"+ wheels over stress them, greatly reducing their life.
I wouldn't buy any of the Sunex stuff, including anything from Matco with RL or SL in the model number. Their stuff is also sold in some of the other "boutique" brands in their lesser lines, but I don't have the vendor codes handy for them.
I am currently using a Matco that I have had for about 20 years. It has performed flawlessly. If I were to buy one today, I would probably buy the Snap-On as I have the straight as well as the cutoff wheel model and love them. They're easily adjustable, quiet and torquey.
While I have no experience with IR die grinders, I would believe the others, as I have a few IR air tools that are awesome as well.
I have the IR301, I've used the heck out of that thing, very handy. I realize the straight ones may provide a little more torque, but there are many times when you don't have the room, the angle one will squeeze in. I like to run those 2" 3M Scothbrite pads in mine, best method for getting old dried gaskets off. Just make sure you put a few drops of oil in it every time you use it.