Just finished Sub & Below Zero! Both are good

BUT. Subnautica breaches my top 10 games, Below Zero does not

I'd say Sub is a 9.5/10, Below Zero is a 7.5/10. There are distinct aspects of Subnautica that I just enjoyed a lot more:

1) the Aurora was always there to help orient myself. You could see the stern, bow, mast, from practically anywhere, and be able to tell where you are. I spent practically no time near the surface on Below Zero because the surface just wasn't distinctive and was clouded by storms half the time.

2) I felt that the biomes transitioned better in Sub. I also knew that wherever I was, I could swim down/up, and biomes would connect. Then it was just a matter of orienting myself relative to the Aurora. I didn't feel this in BZ. As a matter of fact, I set up base over the tangly forest, and pretty much just hand to swim linearly back and forth E/W to complete the game.

3) I didn't like the PDA voice-over in BZ. Giving the voice an English-as-a-second-language accent made no sense, and robotic zingers lose their punch when delivered by an Indian lady who keeps pausing before the punchline and delivers every single one in the same tone. It wasn't bad. It just was never funny, it didn't feel like an emotionless robot, and it lacked compared to Subnautica's.

4) I didn't feel compelled to explore anything that I didn't need to in BZ. In Sub, I was surprised that when I finished the game, I'd gotten all the Steam achievements. The game subtly made everything there was to do important and in-my-way enough to make me do it. BZ does not accomplish this. I didn't bother with spy penguins, because I didn't see the point. The sea truck only had a depth of 150 meters, so I immediately made a PRAWN and just used that for the rest of the game.

5) I guess the stasis-rifle was removed because it was too gunny and the creators didn't want us killing everything, but I no longer felt compelled to interact with the dangerous creatures when I couldn't get near them as a result. Further, the AI on all the creatures felt gimped. The only danger I experienced in BZ was running out of oxygen. The leviathans all behaved identically, chasing you, trying to eat your PRAWN, then leaving you alone long enough to dismount, repair, and be on your way. None of the sea monsters felt like they had character, except the sea monkeys. I loved those little bastards.

So, yeah. Overall, BZ is still a good game! Some parts of it are better than Sub, like adding the oxygen plants, and the Recycler. But it definitely felt lacking in comparison, in particular with the incomplete Sam storyline (I was under the impression that we came to the planet for vengeance for Sam, but the story goes in a completely different direction), with the abrupt end of interactions with Marguerite, and with the modestly lower quality of the map & AI. That's my two cents. I don't complete single players often these days, and I did finish both of them, which imo is a testament that they're both excellent games. I'm glad that I played them.