I've had several of these:
Original Harbor Freight single speed: Cuts great, very noisy, high vibration levels, had it about 6 years and it keeps going and going and going. Tough as nails.
Menards Performax Variable Speed: Same as HF Variable Speed. A much nicer unit with much less vibration and lower noise levels. Cuts good too. Preferred as the variable speed is very useful many times. For these tools, sometimes precision and gradual cuts are more important than brute speed.
Ridgid corded JobMax Variable speed and Ryobi 18v Cordless Jobmax compatible: Ridgid corded is functionally similar to the Performax variable speed but has more power so can cut things faster. The Ryobi cordless for me is my go to most of the time as I'm not always next to an outlet, so where I need the OMT functions of cutting, sanding, etc but away from an outlet, that is king. It's about the same as the Ridgid functionally.
When I can plug in, the Ridgid or the Performax are my go to ones. Cordless is the Ryobi. The extra Jobmax heads are just a great idea, though I don't really think they are as good as separate tools because the vibration method to drive them isn't as good as normal tools, but close maybe 80% as good. If you have Ryobi 18v tools, it is a must buy to get the Ryobi OMT and then the Ridgid corded too and get all the heads you can use for both. I gave away my original HF fixed speed to my sister, who loves it !
Sure Fein is great, Bosch is good, Dremel low vibes (civilized OMT), Rockwell tough as nails, etc. But these things just vibrate their way to success and they all do that. The cutting blades are more important than the tool vibrating the cutting blade is. So I would go fairly cheap and get a bunch of blades instead with your money, unless you are a pro. The only one I wouldn't get anymore is the cheapo HF single speed, but the variable speed HF is just fine or Performax. Rigid is step up from there and Rigid or Ryobi for cordless.
Also you can re-set your cutting blades once they get dull. Only the very end has short little teeth on it. You can remake your own teeth on them easy and keep going with a blade till there isn't much blade left. Also, if you ever have to make a cut back towards you, you can bend a blade around and get it in there and go to town with these! Only precision tool to safely cut things backwards known to man! Sometimes just an essential tool to have. - Paul