I think you need to make a decision based on a sample of more than one ball.
Here is what I know.
Seamless balls are the most durable (averaged over time), cheapest, have the highest bounce, and are relatively easy to transition to from celluloid. I recommend these the most for people who are first starting to play with plastic. But they are harder to spin and probably the spin affects ball flight through the air more than other plastic balls and definitely a lot more than celluloid. When they break they shatter. This usually only happens when they strike an edge very very hard. If that doesn't happen, they last an amazingly long time. They are sold under many brand names (for example XSF, Palio, Nexy, Yinhe, and now some European companies are offering a seamless option). I have found they are identical except for the label. Reports of roundness vary. I think they are ok usually, but you will find some eggs in a box now and then.
Nittaku Premium (Japan) 40+, which I will abbreviate NP40+ plays most like celluloid, is by far the roundest, smallest, lightest, and quite hard. Some people say they feel like little rocks and mistake this for being heavier (but I have weighed them carefully, they are actually lighter). Has medium durability (by plastic ball standards) and I think is about the same durability as Nittaku celluloid. In general they don't shatter, which surprised me about your comment. The external surface discolors and mars most rapidly. The are the most expensive. I personally like their playing properties the best.
You other options are for now limited to seamed balls made in China by either DHS or Double Fish factory. There is sentiment out there that Double Fish balls are better than DHS and I agreem but they are more or less the same. They are by far the heaviest when you weigh them, so much so that ITTF will not approve them come January unless they change. By far the least durable, expensive, and the lowest bounce, and hardest to adjust to. Some people will prefer the lower bounce for their style once they get used to it, because of their playing style. Most plastic balls are in this category. I will personally not use any of them if I have a choice. The bounce is way too low for me.
Butterfly is offering a ball made by a factory in Germany that is different, but as far as I can tell it is only sold in Europe and I haven't been able get any to try them. I hope they are better and suspect they will be.
All of the 40+ balls are a little larger than celluloid. NP40+ are lightest, Chinese seamed balls are the heaviest. XSF is in between. The larger diameter means they
all have less spin than celluloid and fly slower in air.
All seem to have rougher surfaces than celluloid. This surface roughness affects ball flight through air, and also means they react more with the table, so spin you do impart on the ball does not always persist to your opponent's racket because spin energy is dissipated in causing changes in ball trajectory and bounce. Of course that was true for a spinning celluloid ball, but it is more true for new ones, especially seamless.
This means that you will make constant little errors until you get used to this. And do not not underestimate the time it takes. When people push at you, the ball will sort of stand up and not bounce the way you are used to. The balls fall faster, so you will find that when you are away from the table, for awhile, you will be letting the ball drop too low before you hit it. Serving is especially hard to get used to. You will expend more energy playing. Be patient, in time it will all feel normal again. I actually quite like them now.
I have reached these conclusions based on 18+ months playing almost exclusively with plastic balls. Also our club has run tournaments with several brands. My samples of each of the various ball types is large and extensive (I was the first loud vocal advocate of seamless balls on English language websites). In other words, I am not saying these things based on one ball I hit with for an evening, this is based on pretty intensive study and hundreds of hours of playing time.
Once you are used to plastic balls in general -- give it at least 6 weeks -- you will find that each of the three main classes of them have their own distinct playing properties. I like seamless and I like NP40+, but if I play for a week with one type, and then switch to the other, it takes me about 90 minutes before I feel comfortable.
Of course, NP40+ biggest problem is they are almost always back ordered and hard to find.
