I’ve spent a lot of time driving Ford and GMC fullsize vans. The GM is better in every way. Both are very durable and reliable. The GM rides better, handles better, is more comfortable, roomier and is finished a lot nicer. The Ford is very outdated, it’s very 1990.
The longer wheelbase makes it ride and handle better. The larger doors make it much easier to load and unload bikes.
You can’t get the 5.3 in an extended GM van, it’s 4.8 or 6.0. The 4.8 is a good bit better on fuel and has been very trouble free. Our last 2 vans were Fords with the 4.6 and they’ve been reliable too but the GM’s were just nicer all around. Both are good, but if you have to pick between the two, all else being equal, I’d suggest the GM.