First thing to note, oral and vaginal are very diffirent in sensation, a sleeve cannot mimic both. Best is to not even try to aim for that as it will just dissapoint. A general versatile allrounder is therefor the way to go. And these are often closer to vaginal than oral.
For machines i would generaly just go for centered orifice sleeves. Off center does work, but when swapping sleeve types, its very quickly going to be anoying if you need to change settings every time.
For oral, the turbo and boost sleeves are currently the best around. The inner rings do a lot here to mimic tongue behavour. Especialy when it gets angled.
I dont know if boost sleeves can be used in an OSR/SR as the cases differ slightly, but the turbo ones do, and are great for it. These have a centered orifice, but some of them can in theory also be used angled (as the frontal ring often has some side holes).
Also, dont blindly listen to what others say about which exact sleeve to take. Everyone is diffirent and some sleeves can be liked by some while hated by others. Look at which sort of textures you think are going to feel nice, check if you want tight or loose, and then decide which sleeve matches that.
Tightness, and key areas (like lotus nodes or rough/smooth zones within sleeves) matter far more than whether its a block, bump or triangle shaped pattern. And choosing based on these things makes it far more likely you will like it. If you like these in current sleeves, you will most likely also like them in fleshlights (and to me, lotus nodes are excelent for blowjob scripts, even if not realistic)
Also, check how each fleshlight works suction wise. Not all of them work equaly well. Some can actualy disrupt suction when blocking the hole in such way you pull the sleeve out instead of the sleeve pulling on you. The T valve might otherwise bring problems.
For fleshlights its rarely that the first sleeve is going to be the best for you. But its going to set a benchmark which you can use to pick a better one. I would usualy say that trying to pick the most average sleeve is best (or at least a popular one). You can often look at reviews as they often will be compared to those.