I'm a huge delay and reverb fan. More so, delays than reverbs. Have many more of those, than reverbs LOL. Some of the reverbs you folks have suggested are on this board. I took the picture a year or two ago, just for the collection. They usually reside on different boards and are swapped in and out, as needed.
The Ventris tends to be my go-to, for overall killer tones with little effort, intuitively. Sounded fantastic right out of the box. But it may be a little more involved than the OP wants to be bothered with.
I would not recommend the Polaris - at all. What it does, it seems to do well. But, it's nothing to write home about. I started upgrading my reverbs, and once I picked up the Space and the Ventris (and later, others that followed), the Polara was permanently removed from use on any of my boards. I never play through it any more. I should probably sell it, but I can't bring myself to do so. Also...I hate the artwork on it - always have. But opinions vary, and you know what they say about opinions.
I know...knit-picky. I just think it's ugly, on top of not sounding spectacular, like some of the pedals are capable of.
The MXR M300 has six very usable algorithms and couldn't be simpler to dial in a wonderful sound. I think it's also the smallest (?) pedal of the bunch. Stereo (capable) operation with TRS plugs and you can use it with an expression pedal to morph between two different settings on a single algorithm (fully dry on heel, to fully wet on toe position, for example).
The "Pad" algorithm is gorgeous. Gets you straight to Ambient Land. You can chose a higher, lower active mix, or a combination of the two, with a single dial. Its does all the basic utility things (hall, plate, spring, etc.) and does them well, with little effort. It sounds beautiful, in stereo. I've never used it mono, though.
The Afterneath (I have the v2 and v3 models) can get some really wacky, spacey tones, but you'd have to experiment to really dial in something incredible - and they're mono units, if that matters. If you want any kind of conventional (traditional) reverb sounds, try another pedal.
The Fathom is also mono, but I think it does reverb very nicely, for a mono pedal, and is relatively easy to dial in.
The Mercury 7 sounds fantastic, and only has two algorithms. It can be easy to dial in, but you have to get used to the secondary functions on those knobs if you want to use it to its fullest. May be more complex than what the OP needs or wants.
The one I seem to use the most, in recent times, has been the Walrus Sloer. It sounds phenomenal, in stereo- bigger-than-life. But that also has secondary functions that may not be OP's cup of tea. I use this one on keys, as well, and it sounds glorious.