I have 1 x Canon 600 EX RT and 3 x 430 EX III RT flashes, plus a few other flashes (e.g. Nissin 866mkii and 430EX II).
Radio triggering is definitely handy over optical in certain scenarios (e.g. outdoors, behind objects, etc).
The 430EX III RTs are slightly better built, and menu system more intuitive than the 430EX II... plus of course the III RTs have radio control. Sometimes I use the optical trigger from my 80D / 7D's built in flash. Othertimes I use one 430EX III to trigger others. The 600 RT are the best of the bunch in terms of features, ergonomics, build quality (and power).
I also have the ST R3 clone from Yongnuo, and it's great - reliable, better built than the early Yongnuo items, and has a great menu system... useful as it's fairly logical / close to the 600 RT feel / menu. (The ST R3 clone also has a useful AF assist, that the full Canon ST R3 doesn't). Plus having the little / lighter controller is better than having a big / cumbersome flash on top to control other off camera flashes (especially after a long time I feel it in my wrist.)
As I bought all my flashes 2nd hand, it didn't cost me too much... I wait for good bargains! I bought the Yongnuo controller new (for about $70 USD). I also have 4 Cactus transceivers / controllers, which are useful when I want longer range (And which I had before I bought I got into the Canon RT system). They have been a good step up and have some specific / special features, but now that I'm into Canon directly, they are a bit redundant for most of my flash photography, as just using the Canon RT system directly is quicker / easier.
I'm very happy with my options... it gives me a LOT of flexibility, and decent power for pretty much all situations I have need of.
Regards,
PJ