I think you are going in the right general direction with a plant mix. That gives you multiple chances that the deer will actually eat one or more plants in the mix plus weather and soil conditions will tend to favor some plants more than others. The more plant variety you have, the better your odds of having a good plot that deer will use.
As far as the best deer food plot, there is no such thing. Deer are finicky and unpredictable and what they'll eat in one place, the won't even touch somewhere else.
What I'd recommend is to look for plantings that will grow well in your specific location and be honest about your soil condition. Specifics such as hillside or low land, drains well or not, sandy or clay soil, etc. are very significant. Whatever growing conditions you have, look for seed sellers recommendations for your conditions and focus on growing healthy plants 1st - in small plots - so you can experiment next and see what the deer will eat. I say this because no matter how well it grows, if the deer won't eat it, you don't want to bother. The only exception to this rule seems to be Brassicas. For some reason deer seem to need some time to get used to eating them so you may need to grow a couple seasons worth of Brassica plots to get a fair look at whether your deer are going to eat them.
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