Which one would you recommend?
Between the two boards, I’d go for the RK even though it’s soldered because at the end of the day you can still put any other MX switch into it you want if you ever want to try something besides the blues. With the GK I think you get hot-swap, but it will only be compatible with other Gateron opticals.
Get the GK, because you can easily swap in Kailh clicky opticals, which use a click bar instead of a click jacket, which sounds and feels much better.
Between the two, I’d get the GK over the RK as the GK is hot swappable. There’s a level of customizability in the GK at least.
Also, as a side note: The GK61 is also available in a non-optical version which is hot swappable too in case you’re wondering. I have it myself and it’s a great starter keyboard as you can pretty much use any MX style switch on it.