SX720 has a 1/2.3" sensor which is roughly the same as whats in most decent phones these days. The only advantage it has over a phone is that it zooms a lot. It's also got a very slow f/3.3 – f/6.9 lens. In comparison most phones are f2.2 or faster.

RX100 on the other hand has a 1" sensor. It's got no 4k, wifi, evf, pdaf, selfie screen like the latest versions but it does inherently takes pretty good photos and allows for growth if you get into the hobby.

Can't say if RX100 is still worth buying now (I'm still keeping mine) but for sure I won't get the SX720

the panasonic TZ80 also has a 1/2.3" sensor, similar with the canon SX720. IMO, might as well shoot from your phone haha. less stuff to carry around, easier to share.

you can see the large difference between the 1/2.3" and 1" sensor in the pic posted by sniper above. more than 4x the area. Photos from the 1" are sometimes virtually indistinguishable from DSLR photos.

so for image quality, RX100 for sure. no wifi but you can get a toshiba flashair SD card for phone transfers

BUT, the zoom range is not a wide as the TZ80. perhaps the sony HX90V is more comparable.

In addition to dvlzplayground has said... These travel zoom are mainly for bright daylight only.

Once the light dims then gg.

Get Gopro or xiaomi yi action cam for perfect selfie.

G9 or G9X?

Looks like they're recommending you stocks they cannot sell (as always) 

the thing about the RX series is that the newer models will be more expensive

not like smartphones where a new version replaces the old one at the same price..

Sony having anniversary sales on 16 March at Curve fr 6.30 pm. You can test your luck then.