Go for engineered as it is so much easier to fit, will last longer, doesn't shrink or warp
There is a great place near Leek I think called Peak Oak (google it)
We had some engineered oak from their about 5 years ago to go on underfloor heating. It hasn't warped or shrunk. Still looks as good as the day it went in
We've just bought a fair bit of solid oak flooring from B&Q, hoping to get it fitted in the next few weeks. They had a 50% sale on, so we thought we'd get it early. £280 to cover a study around 12 square metres - seemed like a decent enough deal. Fitting should be around £150 I think.
i was in similar situation on deciding on floor, but have decided on solid flooiring. Just have to decide on the underlay / fitting method. Is a new build so wil have concrete floor so have choice of adhesive or using the super sticky underlay with a DPM layer underneath