I'd definitely rather have Kemba if my team was playing today. Lowry hasn't looked well, maybe he's still shaking off the rust.
If the Raps had a healthy Kemba they'd raise their odds of making the conference finals for sure, assuming his struggles are injuries/rust (which is my personal belief), but the actual Finals are still a Lebron injury away for any East team.
The folks saying Kemba should be a 6th man aren't staying current. He made a mini-leap this year in 3pt shooting, he's putting up percentages and volume that are just below the uber-elite (Steph/Klay/etc) in that area. That was always what held his game back, taking midrange shots instead of 3s (and shooting 3s at a low percentage when he did take them), but he's the rare case of a poor shooter becoming an excellent shooter through repetition.
Give Kemba a longer look next year (or if you have league pass check some archived games), he's much better than you remember.
Also, the reason Charlotte fell out of the playoffs was injuries. Zeller specifically, that was the real killer because we have zero depth at C, but Batum also missed time and took weeks to play himself back into form. We went from 4-6th place to 9-12th place in basically a month. In spite of that the team finished near the top 10 in efficiency stats, suggesting without injuries they're almost certainly the 4th-6th type team we thought and not the lottery squad they ended up. They key is to add depth in the offseason and pray the injury gods leave us alone in 2018.