CK20S is a great tractor choice in that size range. I loved my CK20 and cannot part with my avatar photo of it in action even though I've moved on to a DK40se. It is a tough and very capable tractor. Like any machine there are going to be improvements made (eg 20S vs 20 and new loader). I'd expect it to continue to evolve but it is a great bang for the buck right now and I wouldn't hesitate to get another if my acreage needs diminished.
I had a Horst Welding QA adapter on mine which worked beautifully (still have it if someone wants to buy it
). You can however also function with pin mount attachments. If you are only going to switch between grapple and bucket, it is, IMHO, a toss up whether to go with QA or pin. QA is flexible and faster but pin mount costs less and you don't have 100lbs of dead weight subtracted from your net lift capacity.