I have various versions of Encore rifle barrels; 24 inch tapered with iron sights, 26 inch heavy and 28 inch Pro Hunter. I don't think I'll be much help because I like them all.
1. The 24 inch tapered barrels are a little lighter and obviously the gun is a bit shorter but 4 inches of difference between it and a Pro Hunter barrels really isn't that much. I have Warne QD rings on them so if I wish to use the iron sights the scope can be easily removed.
2. The 26 inch heavy barrels are what most would think of as target or varmint barrels. I like them because the absence of iron sights gives them a sleeker appearance. If I were getting a barrel with the intent of shortening it, this is probably the one I would choose.
3. The 28 inch fluted Pro Hunter barrels may, depending on the cartridge, give one an extra 50 to 75 fps in velocity and they look cool; not very good reasons I know. The downside is, that if you want to shorten it, cutting through the flutes ends up making it look a bid dumb in my opinion (sorry). I like the barrels as they are and have gotten a number of barely used ones at very good prices because others apparently didn't like them.
Barrels of any of the above lengths can shoot very well. I wouldn't pick a length because I thought one length would give a more accurate barrel than another length.