Time is money in the wind tunnel, and given that Merida, Simplon, Avanti and Canyon are not well known and/or unavailable in the US, I don't think VN needs to bother testing them. VN has previously tested Specialized Venge, Scott Foil, Litespeed C1, Cervelo S5, Ridley Noah, Felt AR1 (previous model), Blue AC1SL, Cervelo S3 (previous model), BH G6, Trek Madone, and Giant Propel.
To me, it makes most sense to test the new Felt AR, new Cervelo S3, and BMC TMR. And maybe Neil Pryde Alize and Storck Aernario. I think it would also be interesting to test an older skinny tubed bike for comparison (I will donate my steel bike for the experiment