I recommend checking to see if your local shop will service HOG (or Deep Six set from other post). The Mikron does not have the venturi on/off lever adjustment. This is not a major deal if you are using the Mikron as the primary all the time. It is nice to have it off when the octo is hanging out. The HOG is bigger and a little heavier. You could buy a HOG first and second and then buy a Mikron octo then have both. You can decide later what works best as a primary or secondary second stage. I recently picked up the octo for under $150, new. All suggested options seem good to me. I don't recommend not picking up a used set as a first purchase. Eventually you may get involved into servicing your own regs but I see you wanting to buy a set and just jump in and dive it.
To myself, two very simple features found on many modern regulators make a group as top performers with difficulty in distinguishing differences.
1.) Barrel/poppet second stage- Before this design came out, many seconds were the "single lever downstream" design. After the barrel poppet design (some companies call it a "pneumatically balanced second stage") came out, nearly every company released their own version of it. I have trouble naming a current company that does not have a version of this.
2.) Balanced (or overbalanced) diaphragm first stage with a membrane sealed environmental seal/guard/cap-A lot of regulator companies also offer this. The balanced design is almost a sure thing but not the environmental seal. Keep in mind that many (other posters please fact check me!) regulator first stages operate in the 140-150 psi range. This means the seconds paired with them will be often interchangeable with other first stages.
If you have the two above features and the availability to get them serviced (or by yourself), then you actually have a lot of options. My personal favorite is the Hollis DC-(1,2,or 3) with the 212 second (not the 221). There are sellers on Ebay selling them for under $200. The 212 second is light and relatively compact. Some don't like the exhaust directions but I get lots of use from my rig. The HOG, Legend and Apeks ATX seconds that I have don't seem to be that much different other than size and minor ergo variation.