Yeah, understand your dislike of SQ not allowing any further benefit without flying business/first. If you're only flying SQ then you pretty much have to stick with it. If you were talking any other Star Alliance airline in the world it might be a different story... but SQ only releases premium class award seats to Kris Flyer in general.

How much do you actually fly and what types of fare classes? Also do you have a typical route or is it all over the place? If it's always cheapest economy then you won't get much love from other programs in Asia, even if you switch your loyalty. Depending on your needed routes, maybe it's worth looking at CX, maybe it's not.

I didn't realize that you only have to spend 15k a year on a SQ based credit card to hold Kris Flyer Gold, that's very cheap and an easy way to keep status while looking for greener pastures.

I'd be looking outside of Star Alliance as Kacee mentions if that's the direction you want to head. It doesn't benefit you at all to have 2 different *G memberships. If you went Skyteam then you could possibly start flying GA more, or if you want OneWorld then obviously CX, but OneWorld programs in general are extremely stingy about credit on low economy fare classes. I believe AsiaMiles credits at 1:1 regardless of fare, but you would not have that same benefit flying other OW airlines.