There are two downsides to Chase. First of all, Chase doesn't have as many transfer bonuses as we typically see from other programs. Furthermore, Chase doesn't have as many transfer partners as other programs.
That claim has very little merit in my view. Chase has UA and SQ as transfer partners, which means that, by extension, since UA and SQ miles are good for booking award tickets on any *A carrier, Chase has 26 possible transfer partners + some partners of *A carriers. I know this because I seldom redeem my UA miles or Chase UR points to fly on UA metal, despite UA MileagePlus having been my primary FF program for over a decade and I am UA Million Miler. I almost invariably use UA miles and UR points to book award tickets to fly on other *A carriers, especially those in Asia (TG, BR, AI, CA, OZ, NH, in addition to SQ).
I also think it's important to point out that Capital One has Turkish Airlines as a transfer partner, as there are some unique redemption opportunities there.
Maybe, but how much more valuable are those "some unique opportunities"? I consider TK a redundant Chase partner when one already has UA and SQ.
As argued before when the Cap Vx was being pushed aggressively, I believe that the CSR + CFU combo easily beats Cap Vx in points earning potential (everyday or otherwise)...
So, YMMV.