Compared to the likely competitor (Samsung), removable batteries. But the more I play with the second screen, wide angle, fingerprint sensor that I can do one-handed---I'd say I'm pretty happy, enjoying the feature set and not likely to switch again unless (a) I'm really disappointed by a new version; or (b) really blown away by a competitor offering.
I'm averse to switching in general, to be sure. It's troublesome. The company arguing for a switch has to make a stronger-than-normal case, versus starting fresh. You can do this "well, this is better here, that's better there, pros, cons, etc" until the end of time, all mostly about incremental things except for deal-breaker issues. For me, the three deal breakers or close to deal breakers are sd cards, screen size and (although to a lesser extent) removable batteries. Then, we can negotiate.
Most other things are in the line of "incremental" these days. Every top phone I've played with does well on typical stuff like cameras, call quality, screen resolution. Pretty much any of them will suit my needs on other and standard issues. At the moment, the only thing I'd say I don't really like on the V20 is the lack of a light showing it is charging and (more importantly) fully charged. If that's the only complaint versus all the good, it will take a lot to make me switch, no matter what incremental improvement comes down the pike.