Yeah, I'm similarly torn between a few prospects, including Poku. I really like him... In theory. But I can't watch even a single game of his without endlessly wondering whether he'd ever be able to hold his own in an NBA court - not just in terms of the players he'll be going up against, but the physicality, the quickness, the body-intensity. I know he's really mobile, but I just can't shake off the Porzingis comp (who yet again got injured before finishing out an NBA season, even being more rested for these playoffs than he'd ever been in his career). And Porzingis put on a of a lot more muscle than Poku could realistically hope to gain - yet tendons and cartilages just aren't something you can work on and add muscle towards. I'd rather go for a higher floor prospect - which doesn't necessarily mean they have to have a lower ceiling than Poku, tbh.
Regarding Precious' ability to shoot from outside, I have yet to see video evidence that his shot isn't mechanically sound. Yes, he doesn't shoot volume, yes, he has bad percentages, but so far I haven't seen a true "can't be fixed" aspect to his shot. I don't care that it's slow either, since I'm not expecting him to become a volume shooter, I just need him to be able to keep defenses honest by draining open shots. If he can do that, and considering his driving and faceup game, it just opens up a lot of possibilities for him as a perimeter (big) player; that is the true value that I see behind Precious, not even mentioning his defense.
If everything goes accordingly development-wise, we could be dreaming of a starting lineup of White-Lonnie (bye DJ, I said this was a dream...)-Keldon-Luka-Precious. You have 5 above-average defenders (jury's still out on Luka ofc but IMO he has shown promise), switchability, outside shooting and playmaking, rebounding. Luka can take on the heavy shooting load, he shown in his last game that he's willing to let it fly, and Precious gives you the things Luka doesn't - vertical spacing, hustle, rebounding, lob finishing, bulldog mentality from your big. To me, that looks like a really balanced and modern NBA team, for sure could make the playoffs (again, if everything goes according to plan).
Btw, I don't know why you said you disagreed with me then said we definitely need to tank next season, since that's exactly what I suggested. For sure we have to do that, next years' class is rumored to be absolutely loaded with talent at the top, and as you said a lot of SF-PF type players, which would be precisely what we'd be missing if we took Achiuwa, who projects to be a PF-C kind of player.