m.2 nvme ssd 128gb or ssd crucial bx500 240gb

If you want the fastest boot, go with a M.2 nvme drive. 128gig is more than enough for windows and a few other programs ie utilities, etc. I just checked my M.2 and windows enterprise, office 2016 and a few utilities are using approx 35gig.
You are not going to install many games on a 128gig drive so IF you are going to install games, then get a mech drive 2TB or so for the games.

When you install windows, be sure and have ONLY the M.2 installed. Win10 setup will place it's boot files on a drive connected to the first sata port. With only the M.2 installed, setup has no choice but to install all files to the M.2.

Be sure and go with a quality drive ie samsung or intel and check the read/write speeds; not all drives are equal.

 

BTW both my intel and ryzen systems use samsung M.2 drives and boot windows in about 5 seconds after POST.

 

If you made me choose, the asus. Personally I would go for a board running the x470 chipset. Something like this asrock;
https://www.newegg.com/Product/Product.aspx?Item=N82E16813157835