I've had all 3- one thing I've got to mention is that if you have the SX Jazz, you probably won't like the Affinity Jazz bass either. What about it is not comfortable or don't like about the sound?
Out of those 3 options, I would say the GSR200 - the P/J pickup should give you more variety in tones, be lighter, slim neck etc.
The Cort Curbow 4 (I'm assuming this is the older luthite body ones with one pickup) are very underwhelming in terms of sound-it's primarily a slap kind of bass more than anything, no deep lows. It's got the active preamp unlike your two other options but even then, it's somewhat limited. I've had five of these, loved the size (full scale but with the smaller body, fits in a regular guitar gig bag), the look but couldn't get over the lack of sound. I slap a lot but even then, it couldn't give me a better variety in tones- I've tried to like them..lol. Necks are a little suspect too and not quite as stable- it needed adjusting frequently.
I don't know if these are your only options or it's within the price range- but I would probably opt for these two other basses - Squier VM Jaguar or an Ibanez TMB100 like the one I have in my user pic. These can be had for under $200 used - mine was $134 as a scratch and dent special.
Reason why I'm recommending these basses are that they have the P bass pickup and Jazz bass pickup - (the GSR200 also has this configuration). For blues, a bass with a P bass pickup is perfect with a jazz bass pickup to vary up the tones.