I am based in the UK and will post a short review of every diaper I am familiar with. I am slim (31" waist), have mild incontinence but use a diaper mostly out of choice (realistically I could get away with a pullup or even occasionally pad but I just prefer a diaper for ABDL reasons). I only use medical type diapers as I just don't care for age play IRL and I also have to attend medical appointments and don't want anyone to think twice about what I'm wearing.
Tena Slip Active Fit - nice smooth/soft plastic product. Excellent tapes. Great absorbency if you get the Maxi or Ultima. Not that bulky for the absorbency you get. Drawback is that when worn and fully wet the padding inside will clump up and break apart. It stays within the nappy but the integrity of it gets bad.
Dry Life Slip Super - has a more comfy, bulky feel to it than the Tena. A bit more noticeable when worn under clothing but not much. The padding holds together really nicely, even when very wet, unlike the Tena. The plastic has a nice crinkle to it. The shape of it on the body feels a bit more traditional (like a baby diaper).
ID Slip PE backed - I haven't ordered these for a few years. They used to be a good alternative to Tena, particularly before the Active Fit was released and they didn't have a good plastic backed option. If you can get them cheap, they are worth trying at the higher absorbency ratings. Only the PE backed though. The cloth backed are really poor, sag a lot and feel leaky.
Abena (plastic backed) slip - poor. Not enough sap so the absorbency isn't great. The padding starts clumping after just one wetting. It's also a very big fit on me, the back rises up very high on the back compared to most diapers.
Molicare - better than the Abena but similar in the sense that there isn't really enough SAP and you will get clumping too soon after wetting. I really like the colours though. It's just neat having a dark blue diaper that is still medical. They ride very high up the back as well, they just have a large form factor. Very crinkly. I have a soft spot for them but they aren't actually a great diaper to use.
Other notable mentions:
Tena Slip from circa 2012 to 2014. That was the golden age of plastic backed medical diapers. They were so slim. The SAP was incredible with how much they could absorb. They had a unique soft feel to the plastic. The tapes were re-tapable and were awesome. It was such a good diaper and when they discontinued it in around 2015 I was gutted.
Random diapers in China. They have some really cool stuff just on sale in regular pharmacies in Hong Kong and China. Covered in patterns, love hearts, bears. They are really cute. The plastic is so thick and solid, with great crinkles. They aren't super absorbent but they are really cool and very available.