A Fortigate 90D is old ?. I still have a few 50B and 60C running ;)
I think any of the models you mention would be great, but what types and how many interfaces do you need? Do you plan on 802.ad links in the near future?
Have you looked at the 100E ? It will give you more if you need port capacity and link aggregation. It does come at a cost approx 300-400usd more than a 90E in hardware cost. It also has the RPS power function available also.
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