I have in-depth reviews for compact rowing machines discussed here so if you want to learn more, check those out. This comparison is designed to help introduce you to these rowers and understand what separates them at a high level.
Often called the Peloton of rowers. I believe this is a nod to the end to end build quality of the Hydrow rowing machine. This means the build quality of the machine, the compact rowing machines and resistance, the user interface, and content available. All of these are done so well. When you sit down and start rowing on a Hydrow, you instantly know you are on a high-end machine. But it does not end there, much like Peloton is known for having a great variety of content from many different instructors, so does Hydrow. The Hydrow content is well produced, has a good variety of instructors, offers different row\exercise types, but also very scenic due to being filmed on the water. These rowing machines break down into two main categories, instructor led or gamified. Hydrow is an amazing instructor led experience, but make sure that is what you prefer over the gamified experience.
This is a gamified rower and it is a beauty. It is the only water rower on the list which offers a little bit of a different resistance and feel when rowing. Still fantastic and a personal favorite of mine, but you can feel the feedback as it is a little less mechanical and I like that. As far as user interface and content goes, it is so well thought out, clean, and extremely enjoyable. The user interface breaks down your options extremely well and guides you to the activity you want. While this is the the case with most connected fitness options, anyone would be able to jump in and easily use the Ergatta. In regards to content, it does not overload you with options but what they do have is top of the line. Push programs, interval training, races, and open row options give you different ways to row. Personally, I love the training and races. Training is great because it provides an entertaining way to learn how to row better and control your speed and power. By matching targets in the games you earn more points while learning to row better. Racing is always a blast as you compete against others in a very motivating structure. This is where I spend most of my time. It automatically places you against people around your current skill level which helps to get the most out of your exercise as you push harder to place higher.
The other gamified rower although very different from the Ergatta. This rower functions more like the Hydrow from a resistance perspective as it is not a water rower. Another very high quality compact rowing machine that does not have you second guessing your investment from build and content perspective. The biggest draw for me of the Aviron is the variety of ways you can use it. It has a massive library of games, is building out a multi-player platform, compete against athletes, scenic rides, just row mode, streaming services, and YouTube integration among other things. You can truly do something different every exercise with this machine. It is also nice to match up your exercise to what you are feeling that day. Race against others, play games, compete against a professional, or just watch a show. They also seem to be constantly adding major improvements so this rower will only continue to improve.
If you have ever used an iFIT product before, you already know what this is like. It has the same user interface and content structure of other iFIT products. The user interface is easy to use and filter down to the row type you would like to do. They have large library of instructor led content. This allows you to switch up exercise types, find instructors you prefer, and like the Hydrow enjoy scenic water locations while you exercise. Other modes such as map your own route allow you to switch it up. The rower from a quality perspective is a slight step behind the other three but not far behind. It does come in at a better price point and if you have other iFIT products you do not have to add another subscription fee. I have heard the 2022 model has improved the rower quality and I be testing that model shortly. Join the mailing list or check back shortly to learn more about this model.
I have linked more in-depth reviews of each rower if you want to learn more. In short, the RW900 is slightly behind the rest but will not cost you as much. The other three are basically equal from my perspective but each offer very different experiences. This makes it so you do not need to worry about quality and can more focus on which offers the exercise type and content you would most enjoy. Good luck with your decision!