Imho...choice buoyancy aid v life jacket is often a mixture of personal choice (hopefully based on training/experience!), organisers/event "rules", sailing area, traffic density, and even...whisper it...age/health/commonsense?
I use both BA (as a one-time dinghy racer, I believe I fully understand their advantages) & LJ, usually not at the same time!
However, on some occasions I have even ended up wearing a 150N auto LJ over a Tribord (Decathlon brand, as mentioned above, I find them very good value. They are warm, as well as buoyant) 50N gillet/BA. Works for me!
Recently, as a result of new health issues that would severely worsen my chances in the water, particularly when sailing alone (the frequency of which has significantly increased in COVID times) I have promised my wife that I will wear an auto LJ "whenever I can". I also now carry a VHF and a PLB on my person.
In the past, on grounds that I was fit, comfortable in the water, and get personal survival training regularly (work) I most often didn't bother at all - BA (at most) met almost all needs. The LJs stayed in the cabin.
Over the years, I have accumulated a selection of 150N Auto LJs, and the older ones with harnesses, hoods and lights etc are really heavy, bulky and uncomfortable for extended wear. Having done a course years ago (work), I service 50% of these each winter. Several have consequently been condemned. One of which was a SOLAS approved 275N twin chamber/twin firing head item, of commercial origin; it won't be missed on my BRe!
I have been impressed with friends new-gen Spinlock deck vest LJs.
So, I have just ordered one of these - teamomarine.com - Offshore 170N back tow lifejackets, which I hope will prove to be the "next step evolution", and will meet my needs as a single hander in quiet(er), colder waters?
If I'm going to end up being towed while clipped on, face down - single handed is not an option!
Will be interesting to hear others "philosophies".