Firstly, Hi & Welcome to AGU
Um.. I'm not really the best person to give advice as I'm currently in a bit of a quandary myself. Potted history. I shot the loopy .22 for the best part of 30 yrs. Changed to girly .177 and loved the flat trajectory and speed of the shot. Then some bloke called Les on here suggested .20. So I've given that a go.
Basically it's the perfect hunting calibre As far as I'm concerned, fast flat and hits like a flying brick.
I like it So much so that I'm going to be selling everything else.
Might I suggest you get along to a local airgun club and seek some opinions and have a go with the various calibres. Most clubs have a wide and varied assortment of shooters and guns, and most will be more than willing to impart their experiences and let you have a go.
As far as Daystates go. I personally can't fault mine for reliability and ease of use. If anything I could do with a slightly longer stock. But that's the same with most of my guns.
I ain't a small fella.
Hope this is of some help to you
Martin