A 4D Free Spin would be a plausible fit, in my opinion. It would fit nicely on that plot of land, and I guess it wouldn't necessarily be too thrilling for Drayton's audience either, particularly if they went with the smaller version like Tumbili or Dragon Slayer.
It would also be relatively par for the course with some of their past ride investments; they do seem to like UK and European firsts, and doing weird things that no other park in the country is doing. Look at things like Shockwave, Apocalypse, Stormforce 10, G Force, Maelstrom... I reckon an S&S 4D Free Spin would complement those nicely.
It's also possible that the park could have a working relationship with S&S from when they allegedly designed a coaster to replace Jormungandr for 2018 (that later got scrapped as a result of the Splash Canyon incident and its effects on the park).
I have a different suggestion from the S&S catalogue, however. This might be a bit out there... but what about an S&S Axis? As far as I know, no park in the world has currently purchased one, it doesn't look like a prohibitively expensive ride type, it would be quite versatile by virtue of the seating, it would fit in well with Drayton's previous history of firsts, and it could also live up to the MD's billing of "one of the best coasters in the UK" based on the very superlative comments I've heard from those who've ridden the prototype.
If I had my way, though, it would be a nice family launch coaster or woodie! A fun and thrilling ride with high rerideability is something that Drayton Manor would benefit immeasurably from, in my view.