Which RMR ready model PPQ?


Regular Member
Network Support I
So I am thinking about buying one of Walther PPQ pistols for my next purchase(and yes, this is partly from the various times of exposure on P&S, and also trying to support the shops that support the network) . Lord knows I don't need another Glock, but the older I get the more I really like an RMR on my pistol. I also really like the low frustration experience of putting together a RMR on a Glock MOS(with the help of the $16 Amazon kit).
It appears that Walther is offering 2 models of PPQ RMR ready pistols........the Q5 match and the Q4 TAC? My initial questions are :
Are there any other 9mm RMR ready models?
Of the models offered, what are the strengths of each model over the others?
Thanks for the help and advice!