This will be quicker answer than what you expected am at the car line. I have to say that I buy what I think I will like. So whatever I currently own, are more or less keepers. None of these are the same and each have an interesting feature, roots or development history. As an example of interesting development history, the Galil Ace has of course one that goes in parallel almost with the very history of the Israeli nation. The PS90, it's design that's way ahead of its time, so way ahead that it's still used in current sci-fi shows.
As far as cost is concerned, while bullpups can be pricey, so are SBRs, after paying for the stamp and the wait. Even those with braces end up to be several hundred dollars over its base price. As far as overall like, fun guns, the PS90 and the subs suppressed are probably the best to have. They're portable, they can deliver a punch depending on ammo, and they go pssck, psssck, pssck.