What software do you have? Lightroom 6 has pano stitching. It works well. The Samyang 14mm f2.8 is a favourite with many, as is their 24mm f1.4. Generally on lenses etc. you might find this site informative.
http://www.lonelyspeck.com/lenses-fo...y-photography/
In my experience it's difficult to avoid spending money on this pastime.
Peter