You'll get almost as many opinions on this subject, as you would on an oil or tyre thread, here's my opinion.
I have fitted an RDL (Russell Daylong) on the ST1300. For me, good for 300km rides between stops, 600km plus days. Others will ride double those figures.
The RDL provides plenty of support under the thighs, takes a bit of pressure off the backside, and has some wrap around support, helps me to stayed centered on the saddle. The pillion section has a little rise at the front, stops the pillion from sliding forward on
some quick stops.
Here are some pics from the RDL website:
https://day-long.com/gallery/honda/Mine is very, very similar.
The problems with RDL is that you need to ship your saddle to the USA, and be without a saddle for two or three weeks, hope they get it right, or go through the process again, and the cost - probably around $1,000 once shipping is taken into account. Pete and Marcus will be along soon with actual costs.
I'd be taking the bike to a local motor trimmer, show him the pics, and get him to make-up one for your. There's MJM in Goulburn NSW that will do that for you. I have a couple of mates down here in Melbourne that swear by him, but he is in the $600 to $700 range.