I've stayed at DI&S once, and PVI maybe 5-6 times. Clearly, we see where my preference is

Here's my basic comparison/contrasting:
Location: Obviously, PVI is closer by a few feet. While DI&S isn't much further, we had a room about 1/2 way back, which was annoying for me, because I was having to walk half way to the back of the property. Considering I'm a "half-marathon a day walker" at the parks, I may get a little testy having to walk "so far." I realize this sounds ridiculous though!
Property overall: I prefer the outside aesthetics of PVI more--love the Mission influence. Does it make or break the stay? Of course not! But I like it more.
Staff: PVI is all over this. Our first stay, I realized I had lost my engagement ring sometime between showering and checking out. They opened the room back up for us, and a maintenance man helped DH scour the room for it. And, the maintenance man found it, and handed it right over. On that same stay, they called each night around 7pm to see if we needed anything. On another stay (specifically, our honeymoon), my dad wanted to pay for a night of our stay. Somehow, when he called, he wasn't getting across what he wanted to do--that he wanted to pay for a night of our stay, not pay and add a night on to our stay. So, when brand-new-DH and I were talking to the front desk person, we explained that Dad wanted to pay for a night on our reservation, so we would be refunded one night's payment, and they finally got what he was trying to do, and completed the transaction without a problem. In our jacuzzi suite for our honeymoon, they had a sweet note about starting our lives together, and we were given two coffee cups with candy. Nothing amazing, per se, but it was fun to receive, and each time I see our PVI cups, I get the warm fuzzies. When I ask for them to call a cab, they call a reputable cab company. Their staff isn't overly chatty, which I appreciate

I have some serious social anxiety, and I suck at small talk, so chatting during hotel check in/out drives me batty!... Okay, on to DI&S. First stay, our plane was late; we were delayed on the tarmac at PDX, then had to circle before we could land at SFO (I think it was SFO, but I could be wrong), had to wait for 60 minutes for our connecting flight, and then we were stuck on the tarmac there for another hour. When all was said and done, we arrived at SNA around midnight. DI&S had started calling us while we were on our first flight to see if we were going to check in. Called them while on the layover, said we were on our way but planes delayed, it would be around midnight to 1am before we checked in. They said it was fine as long as we didn't need to park a car. Explained we didn't need a car, we would be there by 1am. So, they called again at 10pm. Were we coming? Repeat conversation as above. Then, at 12:15am, repeat the same conversation again. I didn't answer their 4th call, as we were pulling into the parking lot. "We thought you weren't coming!" they told me. The stay was "fine." With how cheap their prices were, I made reservations there for our next 3 trips at like $69/night. However, our real "will never stay there again" issue came when my FIL died 3 days before my next trip, and I forgot to cancel 48 hours before, because, you know, police chaplin and morticians and mourning and arrangements and a distraut husband and HELLO my husband's dad just died, my kids lost their grandpa. So, I called to cancel at 36 hours. It's a family-run joint. They could have been curtious. They could have said, "Wow, I'm so sorry, you didn't cancel before 48 hours, but let's see what we can do since this is a serious extenuating circumstance." Instead they said, "We won't charge you if we can sell your room," but refused to tell us how they would be able to prove it was/wasn't sold for that night. The pending charges went away, so we assumed it had all been taken care of, and the charges had been reversed. Nope! 10 days later the charge came out of our account. When DH called to deal with it, they said there was no manager he could talk to, over and over again, and then said "If you had called when this happened, we could have done something about it." He cancelled all our upcoming reservations... And then we got calls from them months later confirming our reservation for an upcoming trip. Had to call back later to be assured they had cancelled all of our reservations with them.
Amenities: Both have pools. The DI&S pool is indoors, in what I call a "fishbowl." Essentially, there's a big (big, big) picture window, so as people are walking by, they are looking in there. So, there I am, in my swimming suit, looking only slightly smaller than Shamu, and families of people are walking by, looking through these huge windows, witnessing the whale emerge from the sea. Honestly, I felt like I was on display at Sea World. Other issues with the pool: got folliculitis right after a dip in the hot tub, and the chlorine smell was very heavy. (Once I had a maintenance and pool man tell me that a properly chlorinated pool shouldn't smell heavily of chlorine--it should be a light, clean smell.) The PVI pool is outside, but surrounded by a brick and ivy wall on all sides. People on the 2nd floor can see into the pool area, but it's harder to see as people are walking by on the bottom level. It's clean, the water is clear, sometimes there isn't enough pool towels. It doesn't smell. And I've never walked away with any rashes.
Rooms: I've stayed in the 2Q room at DI&S. At PVI, I've stayed in the 3Q 2-room suite, jacuzzi suite, and 2Q room. DI&S room was fine; a little small. It had "plantation shutters" for the front window, which allowed light in during the early morning. The floors were clean (passed the white-sock test). The bathroom was clean. The beds were hard. Holy cow. They were hard enough that I considered going to Target to get a blow-up mattress, or even just sleeping on the floor. I don't care how much I walk at
Disneyland, I wasn't ever tired enough to sleep on cement beds! Of note, others have said they had better beds. The towels were small and scratchy. BFF and I are both "smaller" plus-sized ladies, and the towels were too small to wrap around either of us. At PVI, the towels are larger (suites have had big, fluffy beach towels), and are softer. The beds are firm with a pillowy top on them. 4 big pillows on each bed. Passed the white sock test. Rooms are a smidgen bigger. PVI has been renovated over the last 4 years or so.
Breakfast: DI&S has hard boiled eggs, instant oatmeal, toast, packaged pastries, apples and oranges (with slices in them to "ease preparation," and make them impossible to take and eat on the way, ugh!), milk, juice, and coffee. On our various trips to PVI, we have had: biscuits and gravy, fried potatoes, hashbrowns, bacon, sausage, scrambled eggs, waffles, yogurt, fresh fruit, juice, hot cocoa, coffee (with travel lid cups!), pancakes, bagels, cereal. I think there were some other things too, but our first stay was now 4 years ago, so please forgive me

PVI's breakfast allows us to take a late lunch. At DI&S, we were heading for an early lunch every day because there just wasn't much to sustain us (especially when I won't eat "egg-looking" eggs, lol).
Clearly, you can see where our alligence lies! Remember, if you call PVI to make your reservation, they will give you a returning-guest discount, which will take the price down a bit.
We have also stayed at Tropicana, and liked it. If we don't feel like we can afford PVI, Tropicana is our go-to. No free breakfast (ugh!), but we've never paid more than $130/night!