If you fly and plan only Disney then Magical Express is the biggest perk.
To your thoughts ...
Proximity - really depends. I can stay offsite, not far, drive and am sure am in bed before some folks on the buses are. If you will spend most your time at MK, then the monorial resorts are a big plus. If you do mostly Epcot, then Epcot resorts a plus. The rest, no big deal.
Free Parking - well if you stay onsite you can use transportation so the parking is/isn't a perk. I have AP so it's no perk to me.
Dining Plans - not for me, I can eat better, for less by choosing what I want and combining with TiW card or AP. Even if I had neither I think it's really hard to break even (I've tried) let alone come ahead ....... so what is the perk? MagicBand vs CC.
FP+ 60 days - well look at Disney Springs now ... it's great for FoP and will matter for SWL but other than that, no, nothing is that hard to get.
Extra Magic Hours -
this has always been the biggest perk for us but lately we seem to use less and less (and they've been more crowded). If I stay offsite I can save enough money to do the extras like DAH which is way better than EMH.
Free Dining - isn't free. We call it Complimentary Dining, which means if you pay more for your room they will give it to you. For us it stopped being a plus when we dropped to 2 that time of year, when they took away so many components, when they took away the good plan unless you were deluxe and upped the ticket that had to be purchased since we have APs.
We are past being wowed by pools, activities and some hidden mickeys in our room. We stay on and off, and it all boils down to price for each trip because we'd rather go often and have a nicer room than wake up to Mickey in our room. But we have stayed onsite about 6-7 times in last year as POP has good rates.