We picked a breezy day, alternating wind, because that is reality when you go out on the prairie, etc.  Its almost always breezy.  You can see it in the groups because POI varies more than usual.  Same loads on a 3MPH wind day, versus variable 6-10 here..is about .5MOA less or so. 

These are 6 round groups.  20" AR15, WOA, Shilen Barrel. 100 YARDS.

The group in the middle, in the BLUE Diamond, is 1 shot from each load, fired at it.  So we have 10 different loads (2 different loads, with 5 different powders).  So 10 different loads were shot at same spot in middle.  1.09" group.  Velocity is variable from lowest to highest group about !280 FPS, and it still grouped about an inch.  The point is this.  At 100 yards?  super precision loading isn't that important, nor is powder choice, because as you can see, all the groups are acceptable, and all the groups are around an inch.  The drift around in the wind.  PAst 100 yards, at 200 yards, these would open up quite a bit.

Same thing, except 60 grain Varmint bullets from Berger.  Group in middle still around an inch, with 10 different loads fired at same spot.  I moved POI up 1/2 inch from 55 grain loads, so they would be better on center, not low.  But as you can see, if I didn't do that, the 60 grain load and the 55 grain loads would hit near same exact spot group.

We can also see, overall, the 60 grains were better than .2 MOA average smaller groups.  Because they buck the wind better than the 55 grain. 

Smallest average group 55 & 60 goes to N135.  Then the rest are around 1" average to 1.3". 

I would probably take the 25 grains of Benchmark loads but all loads are acceptable.  I like the case fill, not too compressed, good velocity, reliable, consistent, good powder.  Something wild about the Alliant Varmint load data.  It says max load is like 24.7 using 55 grain bullet, and I loaded 26 grains, and its not even stressing it.  Berger manual is useless too, all the loads so SO LOW.  With 55 grain bullet and 20" AR15 you should expect max loads to generally yield you 3100-3280 or something like that.  26 grains Varmint is only 3,050?  I think my lot of Varmint is significantly slower than the load data lot, or something.  Wildly slower.  Its more like Ramshot TAC in load data probably.

25 grains of N135 using both bullets would probably be good balance choice as well, and not too compressed a load, and just fine too. 

As you can see, all are good choices, all are comparable for what you want, and this data can give you a good idea where to start for your setup.