Range for most client devices (e.g. phones) is limited less by the client hearing the AP, but the AP hearing the client. Beamforming is a way to actively tune the AP’s antenna to amplify signals in both directions towards the current client devices, and Ruckus’ BeamFlex is very good - I never see anyone claiming theirs is better, probably because Ruckus holds a lot of patents in this area that prevent others from doing it the same way.
An R610 is an AC Wave 2 3x3 device, similar to a Unifi NanoHD. An r600 is the AC Wave 1 predecessor, and I wouldn’t recommend installing one today unless you get it very cheap.
There is a very big difference between Unifi and the software that Ruckus offers. There are 4 options:
Standalone - managing each AP individually, with very limited visibility into client devices
Unleashed - the APs make a virtual controller (one AP is elected as a master, and one or two are elected as backups) - I have never used this and can’t comment on what features the software has, but it is meant for small installations
ZoneDirector - their legacy controller, still supported for the ZD1200 line, but gets minimal upgrades - provides similar information about clients as Unifi
SmartZone - their modern controller, and be an appliance (SZ-100) or run as a VM (vSZ) - provides similar information about clients as Unifi
Both ZoneDirector and SmartZone has captive portal options similar to Unifi, but Unifi is much more polished in this regard. I don’t know if Unleashed has a captive portal.
EDIT: Unleashed is free, you just have to install the Unleashed firmware on the AP, or if buying them new you can find them with it already installed