Which rail for the mini 14?

The Ultimak sits lower than the Amega.  So with some especially low red dot optics, like the Primary Arms Fixed Base Micro or the Bushnell TRS-25, the Ultimak rail allows for a low cowitness with the iron sights.  The Amega is too tall for this.

The Ultimak is also slightly cheaper, and a few ounces lighter.

I'd go with the Amega only if you definitely want the ability to add the additional rail sections at 2:00 and 10:00 (which cost extra), don't care about cowitness, and don't mind the extra weight or spending the extra money.  Otherwise go with the Ultimak.

I went with Ultimak on mine.  Install was simple, and it's been solid and rugged so far.

And that is a sexy beast!

I used the Ultimak on my Mini-14. Worked great. Personally don't give damn about cowitness. If my dot dies, pop the QD lever and go back to business. Have no experience with the Amega, so no comment there. Ultimak has been around for about as long as I can remember, so there is that. Stuff that does not work well in the gun world GENERALLY does not stay around long, noted exceptions being Jennings, Lorcin, glock

Ultimak it is then. Thanks guys

How does adding the Ultimak rail affect dismantling the rifle for cleaning?  Does it create any issues that get in the way of removing the stock?

Nope.  Field stripping is unchanged.  With the Ultimak installed, you still just remove the trigger group per usual, then rotate the buttstock downward and off.