First, welcome to the forums and the Wonderful World of Maslow.
Now, your question has been one that has been pontificated and discussed here on the forums ad nauseam. Mostly this will be determined by where you are located, and what is available to you. The recommended (and I would probably say the most used) router is the Ridgid R22002, though there are others (to include myself) that have made other routers work as they live in different parts of the word and the Ridgid wasn’t available or didn’t want to buy it. I will direct you to this post: Choosing a router or Spindle. It has most of the information needed for routers that have been tested, though some of it is dated.
A lot of this choice is also dependent on where you eventually want to go with your Maslow. If you want to keep it with the basic setup and Z-Axis, then the Ridgid may be the better choice, but there are still limitations with that (use of a bungee, etc.). If you plan to upgrade your Z-axis to something like the Meticulous Z-Axis, or something similar to the M2 Z-axis, then the options are really endless. The key to that would be to ensure you can get the router (and really the bit) centered in the center of the Ring to ensure the calibration and geometry of the machine is where it needs to be for proper operation/cuts.
One thing I will advise you get when choosing a router or spindle is that it have variable speed. I started off with a cheaper Ryobi, but it was a fixed speed (25,000 RPM) and though it “worked” it left a lot to be desired as far as quality of cuts (that high of an RPM with how slow the Maslow feed rate is doesn’t really line up for the greatest). I switched to a Skil router that had variable speed (plus it came with a plunge base that I wanted to be able to use for other projects). The fixed base for this router will work (I had to move the location of the Z-motor to the left side of the sled), but the mechanism for controlling the depth of cut was very short and incorporates 3 notches on the side of the router body to get to full depth. It was ok, but depending on your depth of cut, it was a PITA. I was already planning on upgrading to the Meticulous-Z, so it ultimately didn’t matter.
Bottom line, you can do a search of the forum here for routers to use, and you’ll get a good amount of returns. The other place I’ll point you to is the Maslow Manual. It has a lot of good information on what is needed for the Maslow, and is something I wish was around when I first started. It doesn’t have a whole lot of information on what routers to use, but does have quite a few examples of what you can do with your sled and Z-axis upgrades.
I know I just threw a lot at you, but you have a few options as to what you can do. And again, Welcome!