I recently made a pretty deep dive research project of this for my coming-soon Colorado. I internetted it hard, and ultimately came to the conclusion that 99% of what I was reading was people justifying their life choices, and the only way to really learn what I wanted to know was to go look in person... So I took a day and went to topper dealers in the area and wasted a LOT of salesman hours....
The concrete part of the research I was able to find was that ARE had some really nice hinges and didn't have fastener covers on their glass leading to a really nice, high quality appearance. While that's true in a binary sense, it's only the case on a SINGLE model (one aimed at looking slick and like the back of an SUV, but not available with options I needed). The majority of ARE's toppers were not especially different to other manufactures; a lot of extruded aluminum frames , flat glass panes, and fiber glass. I was interested in a particular ARE topper that had an optional frame that gave it the ability to support 500# on the roof. That same model could be had with the solid aluminum windoors with optional boxes. Turns out, that frame is REALLY intrusive, and only supports 500# IF you use the specific rack that utilizes its mounting points (not really compatible with much else). The boxes were also only good for 200#, which isn't much when you think about it. Finally, looking at the fiberglass itself, it was rough. Really rough. The dealer specifically only sold ARE toppers with carpet lining because it was so rough. There was a Jason they had in on trade (and I have one on my current truck), and the difference in finish was stark. I went into the whole ordeal thinking ARE was where I would end up, and I was thoroughly disabused of that notion. Specific to the Colorado, the transition from the top of the cab to the topper looked really off, and seeing it in person, it looks like there may actually be a backward rake to it, but it was hard to tell with the tops up on the rack and not having a Colorado on hand to actually see it. I feel like the model I was looking at was only available with double handles (I prefer a single).
The same dealer also had ATC, and those did not seem especially better or worse than the ARE in any way I could tell. The hinges on the rear hatch may have been a different extrusion profile, but not different in a way that seemed to make any difference from what I could tell. Fiberglass finish was comparable to the ARE tops...
The Leers seemed about on par with the ARE, but I don't recall the fiberglass being as rough. They definitely seemed better styled relative to the specific truck in question. I didn't look super close at the Leers, because...
The Snugtops were far and away the best thing going. For starters, the commercial topper with the solid windoors and shelved boxes is rated for 500# WITHOUT a silly frame, and the boxes were rated for either 250# or 300#. Additionally, the back glass is curved, I don't care about the fastener covers on the glass, and it just looked nice. All of the commercial toppers used the same square chromed latch mechanism, while the Snugtop uses a unique pentagonal mechanism... It's neither here nor there, but something I noticed. The quality was better on everything I saw. The main handle could be set up to be locked with the truck's locks (a few had this, but the integration was much better on the Snugtop). The single, central latch mechanism was also better on the Snugtop. I don't know how I feel about it, but the solid windoors on the Snugtop were fiberglass where the others (where it was an option) were all aluminum. The bottom of the Snugtop also drops down over the top of the bed sides in a way that seems would be helpful ensuring weatherproofing, but I can't say the rubber gaskets aren't good enough all around (my Jason doesn't leak around the edges for sure).
The Snugtop/Leer dealer also had another no-name brand I didn't recognize or remember, and it seemed about the same as the ATC.
I started the day thinking ARE, and I left firmly decided on Snugtop. I owe no one anything, and haven't committed to anything in any irreversible way, and I'm not the type that feels I need to justify my life choices to people. Depending on what you're looking for, I would say each manufacturer probably has something that will scratch your itch nicely. Even the cheapest top would provide some functional security, though maybe not be entirely weatherproof. I was specifically looking for something in a commercial flavor with the solid sides, shelving, and the ability to take some weight on a roof rack.