I've done both of those DPs while on solo trips and I honestly didn't feel like either one was really worth it. Like the others said, the deluxe plan is simply too much food and too much time. I'm a big guy and I love to eat (and can eat quite a bit too), but you will spend several hours a day working around those ADRs, especially if you need to park hop or get to a resort to eat. A few years back I took a long solo trip during the FaWF with the intention of trying out as many Disney restaurants and food options as possible. There were a couple of days I did 3 TS meals and that was just too much food. By the end of the trip, I was so full that I was simply "sampling" my meals and thus wasting money (and food too, which I hate doing). I also had a couple of days where I did breakfast somewhere and then using 2 meal points for a dinner signature meal; that plan of attack seemed to work out the best and it offered me the ability to eat at some of the best restaurants on property too. I don't think I would have considered those signature dining options if I didn't use the plan b/c I can't normally fathom spending $100+ for a meal (they are totally worth it though if you have the means!) As for those snacks, I went during the FaWF and so I got a lot out of those credits, but that trip was ridiculous with how much I ate. I probably could have made a decent dent starting up a WDW food blog
As for the the regular dining plan, this
CAN be a good option
IF you maximize your meals by getting the most expensive food items, but again, it could potentially limit your freedom to actually pick what you want off of the menus. Or perhaps you want an appetizer (not included in the plan) or you don't want dessert or you forget to use up all your snack credits. These things can add up quickly to not making the DP a good option. Plus, all those things can actually ruin a dining experience because in the back of your mind there is a niggling thought that you should have order something more expensive versus something you like or that you wasted food or alcohol isn't included in the plan so you didn't get any or whatever. Paying out of pocket eliminates those feelings as you only order exactly what you want. Portion-wise a QS, TS and snack is an "appropriate balance" is my normal routine anyways but it just depends on how much you normally eat. Maybe you need another QS or snack to get you through the day; just one more thing to consider.
Unfortunately I no longer have the few Excel sheets that broke down my costs per trip using the plans vs paying out of pocket. But I do recall that I generally saved money by paying out of pocket or it was a minute one way or another. For me, it is all about the freedom you get by NOT being tied down by the plan, whether in not feeling like you have to order the most expensive things, or not getting too much food that you waste half of it, or not getting the food you want. The time spent can be a different factor as its nice to slow down and maybe explore different resorts or experience new restaurants, but maybe that doesn't meet your needs/plans for your trip.
With the dining plan, you not only have to decide where you want to make ADRs several months out, but you also have to look at the menus to see if its worth a meal credit if you aren't going to get the most expensive thing or if desserts don't seem appealing or if alcohol or something else needs to be factored in. Deciding six months out that I want seafood or Italian or Mexican food is one thing, but to have the meals pre-selected as well is just too much for me; even if it saves a buck or two.
In short (sorry for the long-winded rambling), do your maths and crunch those numbers. Maybe you can use the DP to your advantage (obviously many people do!), but take into consideration how much you envision actually eating, your travel plans/trip goals, the pros and cons of being tied down to a plan or not.
Tom Bricker has a couple of great articles over on his site; just search for "2015
Disney Dining Plan Guide"