You should certainly download the free demo of the Oakland Aeolian-Skinner from Sonus Paradisi. The Swell organ alone has beautiful flutes and and nice string celeste (strings were a Skinner speciality); and being an “American Classic” style organ it is very versatile – Bach should work well for instance. All it lacks is Oboe tone as such, though you might find that the Swell Trompete, with the box partly closed, could fulfil that function.
Being a medium-sized organ for a medium sized church it's very reasonably priced, and the Extension – which adds stops to each Division and provides a fourth manual – is currently available at a reduced price. However if you want a “big” organ sound you might need to look elsewhere. Father Willis provided exactly what you're looking for, including bold Diapasons. Although the Salisbury and Hereford instruments are somewhat expensive, it is possible to buy either in various smaller sizes, so that you can build up to the complete organ gradually.
Sonus Paradisi Aeolian-Skinner:
http://www.sonusparadisi.cz/en/organs/m ... organ.htmlDemo version of the above:
http://www.sonusparadisi.cz/en/blog/aeo ... ample-set/Five pages of discussion of the organ:
viewtopic.php?f=6&t=15497Father Willis – Hereford Cathedral:
http://www.lavenderaudio.co.uk/organs/h ... /hwss.htmlFree evaluation version:
http://www.lavenderaudio.co.uk/organs/h ... age10.htmlFather Willis – Salisbury Cathedral:
https://www.milandigitalaudio.com/instr ... nstrumentsThe long reverberation times in the cathedrals can be shortened within the Hauptwerk software when you set up the organs, but experiment on the mini Hereford set first in case you find the result sounds artificial.
Performances on Contrebombarde can help one gain an overall impression of an organ – start with the “Advanced Search” page:
http://www.contrebombarde.com/concertha ... ced_searchGood luck!