Deciding on buying refurbish or "brand new" is a personal choice. My wife hates buying refurbish items. Whether it be a vehicle, TV or computer, she hates the idea of buying something that was repaired. For me, I love the "cost savings" idea of buying pre-owned (and fixed). As long as it works and I save money, then refurbish is my default choice. But since my wife has the buying power in my home (especially since its "her" iMac), she picked the brand new purchase method. Buying new or refurbish is a personal choice...
Buying a Mac Mini or iMac is a personal choice as well. If into typical "home usage with NO games" usage and all one needs the "the box", then I'd buy the Mac Mini. Use existing monitor, keyboard, speakers, etc. is great on a Mini. Run it for 2-3 years and if/when it lags, I would upgrade to better Mac Mini. If into gaming, then go with the highest CPU and video setup. Gaming usage does drive one into higher end 27" i5 / i7 CPUs. i7 CPUs are needed for most intense games.
For my home, my wife picked the 2.15" "middle of the pack" box. re: 21.5" with i3 3.2 and better video card. If she plans to run the odd future game, it should do her OK. Not the best but OK. And for her typical home usage (NO games) with limited desk space, this small size screen box should fit her needs pefectly. Especially since we do NOT have existing monitor, keyboard or mouse - to connect to a possible Mac Mini box instead. For my wife, ALL-IN-ON iMac box looks better. NO wires and mixing of different H/W items either - which she loves as well.
Good luck - on which ever you decide to pick...
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