Looking at getting my first full sus, been riding my hardtail for while now with a fair few upgrades.

Ritchey WCS wheelset, Tora 318 Fork, XT Drivechain 1×10 clutched mech etc, Hope Tech 3 brakes

Next thing that has to go is the Specialised Hardrock frame…

So far been looking at stumpjumpers, yeti asr/575, santa cruz superlight/blur

Main riding is rough singletrack but nothing too extreme.

Will probably need to be used as funds aren’t too readily available, any other suggestions?

First consideration is of cause the party’s you have to swap over. I take it your fork is either 100 or 120mm in travel?
If so that gets rid of the 575 and possibly the asr as it would need a longer fork.
The super light and blur are good options.

Fork has a spacer that can be removed to move it to a 130, so that would be ok for a 5″

Trek Fuel EX is a good bet, or Giant Trance.

But really the world is your oyster when it comes to cheap 120mm-ish frames – nobody wants short travel 26in frames now so you shouldn’t have to spend more than £300 for something really quite nice.