@bigbike1 As
@Movie2099 pointed out, it depends on your listening habits. That being said, I will approach this as a music heavy system (with the ability to watch video/movies) as this is how I am set up.
For a music only system, the LS50W are hard to beat and, because of their integrated amps and DSP, play much lower than the LS50. A good approach would be to get the LS50Ws, run them through their paces and then decide if they are lacking in bass. IF they are, then go for a good sub. I do not know where you are from, but the ££££ leads me to believe somewhere under HM's reign. SVS is available in GB and the EU (I believe) and is highly recommended on this site. Unlike others on AH (who shall not be named) I am a big fan of REL as well.
The only thing I have against the LS50W is that KEFs own apps are not as nice as, say, Naim's but I think they are a Roon endpoint now and that makes things SO much easier. In that regard, you only have to use the KEF app(s) during setup and let Roon take over from there.
Your third option of the R3 and Naim Uniti Atom looks like it would be an excellent one as long as you are good with the Naim's limited power (40wpc) but your room is not super huge. Stepping up to the R5 will not give you that much more bass and is more of a preference between stand mount vs floor standing (I prefer the latter in most cases - I had the R500 and loved it).