Buy the Rep Fitness Adjustable Kettlebell.

It actually swings like a kettlebell, which is the one thing a kettlebell has to do.

What was compared

1. Swings like a kettlebell, not a suitcase
Owners describe the Bowflex 840 as 'more like swinging a suitcase' because it ditches the classic cannonball shape. Cleans and rack holds need that curve, and the Rep keeps it while the Bowflex knocks against your forearm.
2. A handle you can actually hold onto
The Bowflex handle runs thin with no rubberized coating, so grip slips the moment your palms sweat mid-swing. Rep's 34.6 to 35mm handle is shaped to stay secure through cleans, presses and heavy sets.
3. Steel built for swings, not just curls
Reviewers note the Bowflex 840 'uses a lot of plastic' and isn't great for hard use, while Rep's compact steel bell holds its shape rep after rep. Push either one hard for months and that's where the difference actually shows up.
4. Yes, it goes heavier. You probably won't.
The Bowflex tops out at 40 lbs against the Rep's 35 lbs (16 kg) and adds a sixth setting. If you are genuinely training toward 40 lb kettlebell swings, that range is real and worth it, but most home lifters never load past 35 lbs, so it's capacity you pay for and rarely touch.
5. Ranked Best Overall, not just Best for Beginners
Gear roundups file the Rep as Best Overall and tuck the Bowflex under Best For Beginners, which lines up with the suitcase shape and thin handle. If you're training long term rather than just starting out, that's the one to own.