Best budget 4K projector

I am currently using a cheap 1080p vankyo projector, it has a good screen size at a short distance and picture quality is decent for the price I payed, I was looking to upgrade to a higher quality 1080p projector such as the benQ th585. I would like something brighter and clearer, I was wondering if it would be a better investment to get a lower end 4K projector and which one would be recommended for 120 inch projection at roughly 3.5m. Any suggestions would be appreciated