I am one person alone or sometimes my parents or a friend might stay. If I was part of a big group I would rent a condo but in my case with 1-3 people I like onsite.
I prefer onsite and have done and have planned value stays. I like being on site. Being able to bounce back and forth between my room and the parks with very little time spent in transportation. I even like riding the disney buses.
Values are very basic rooms and the hotels lack a true resort atmosphere for me. You also have very basic food court options, and very little in room amenities. I am okay with this. But you have to know what you're getting.
I prefer ASMu (stayed there and AoA) mostly because I hate the giant icon themeing of the other values. I know that I am an exception to the rule. Lots of people love the kitchey icons and the larger than life thememing, but I'm not one of them. I actually prefer subtle but well done room decor, lush greenery and scenic walkways, water ways or lakes and themeing that is not Disney persay. Which is why I love MODs and like Deluxes. However if I go in with the mindset of expecting a 'basic' hotel stay I am fine.
I don't mind basic rooms. I'm usually in bed or just chilling watching tv/reading if I'm in the room. I am fine with the shower vanity split. I don't particulary like double beds but if I'm sleeping alone a double bed is totally acceptable.
I'd prefer a coffee maker in the room, and I wish you got the foam disney cups in the values but again workable. I actually do prefer iced coffee and mainly use the coffee maker for hot water. With the fridge I can still keep a few things handy.
I do not mind the basic food court as I tend to eat a quick breakfast/snack in the room in the morning (which is where hot water usually comes in handy) and then eat in the parks the rest of the time. If I do eat at the Value resort then I am pretty happy with a chicken quesidilla or hot dog. I am not a foodie and don't mind food court type foods ocassionally. I average maybe one or two meals in the food court. Mostly I'm just getting ice or water from the soda fountain. Of grabbing some milk for the morning.
I am not a pool person. I sunburn and I find laying around outside in the sun highly overrated. Don't need a pool slide or cabannas or fancy pool features. I do miss a hot tub but I've found at Disney it's very hard to find an uncrowded hot tub so I tend to give them a skip even when at the Mods/Deluxes.
Staying offsite would basically give me the same rooms as Onsite with a big difference. No buses, going back and cooling off in the middle of the day. No Disney Bubble, and no 2nd hand enjoyment of a whole resort of people also in the Disney Bubble.
For the 20-30 bucks I'd save offsite (I will not be staying at any of the really cheap hotels offsite, it's just not me, nothing against anyone who does but I don't like true value stay chain hotels and the level I will stay at runs about the same as a value with only a few extras not at a Disney hotel) I'd rather just be onsite at ASMu.