6mm Creedmoor is a strong one to consider if you want high velocity and low recoil. Stubby case designed for long bullets and AICS magazines.
Newer, high BC 6mm bullet designs need a fast twist and I believe the 6 Creed is specced at 7.5" on a Howa. Not sure who else does this chambering at their pricepoint.
Brass and dies might be a bit more costly but once you have some Lapua or ADG brass (if they ever get round to making it!) and just basic Lee dies you are set.
Not sure what your breadth and depth of experience is with rifles but I would say shoot whatever you have to hand first before dumping cash and finding out the gear does not suit you.
Try other people's rifles/scopes/stocks first, then buy.
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