You can rule out any of the 22s for 1000 yard work unless you go with the very fast twist 1-6.5 or 7 twist barrels shooting the 80-90 gr bullets which are not varmint bullets. The 22 for long range limits your bullet selection and short range effectiveness. Now, 22s at 500-600 yards, they make great varmint calibers.
IMO a barrel burner (6-284 in particular) is not a cost effective long range varmint gun IF you shoot a lot. The barrels in the 6.5-284 last 800-to max 1200 rds, and the 6mm even less. new barrel installed is $500-600.
Great shooting guns require 3 things. very good bullets, very good barrels and very good brass.
Best brass (most common) in order is RWS, Lapua, Norma, Nosler, Federal GM, Federal, Win and finally Rem.
Guys have worn out 2-3 barrels with 50 pieces of RWS brass. Now that is cost effectiveness and top shooting all in one.
take the 6mm AI, buy RWS brass ($1.00-1.50 ea) in 7mm neck down and neck turn. the brass will outlast the gun, same velocity as 6-284 and not a noted barrel burner. That will normally mean 1/3 more barrel life or about $200 savings every year to two years.
Necking down, boy that is tough, that takes about 5 minutes for 100 pieces.
Neck turning, about 1 hr for same 100 pieces.
Now compare that to time spent weighting, sorting and measuring other less uniform brass that lasts 25% as long maybe.
Cheaper many times means less effective and more costly in the long run.
Now if your varmint hunting is 1000 rounds in a day at a Pdog town, then buy the cheap stuff and cheapest barrels as you will need a new barrel when done anyway.