Tons of options out there. I prefer the powder to fill the case to the point the bullet it almost touching or in some cases touching the bullet. This creates a lot more consistency when shooting odd angles. Usually this means slower burning powders and near max loads. For large cases it works best especially in magnums. Less chamber pressure and it builds speed down the barrel perfect in my way of thinking. You don't want to load slower burning powders in anything less than 24" barrels it's a lost cause.

I like H 4350 or H 4831 in the 30-06 to 300 win mag, in the 223/22-250 I really have excellent accuracy using H 380. IMR 4831 in the 7mm-08 works well too. I've stayed away from the Reloader powders but I hear good things. My personal loads can't get much better for accuracy and speed.

Main thing is you don't really want to load a bunch of cartridges at one time until you test them for accuracy. Maybe 15 to 20 at a time until you find that sweet spot by going up and down on powder charges. Even a few tenths of a grain of powder can open a group up or shrink it down. That is the advantage of reloading eventually you'll make loads that are superior to any premium factory load at less than half the price.

Use the Case Overall Length gauge to start with C.O.L. it will be on the loading data. The rest is for more experienced loaders. Buy a caliper it's a great tool if you want to perfect loads that are superior. They don't cost much.