What's a more reliable engine for the mid to late 90's Ford Expedition the 4.6 V8 or the 5.4 V8?

Also how are their transmissions?

They are basically the same block with the 5.4 having a longer stroke.

Expedition is way too huge for a 4.6L. Last I heard they stopped making them a few years ago.

Ahh the 5.4 is nice motor. Just be sure to get the dual overhead cam motor. If you but the single overhead cam motor get ready for 10 hours of fun when you change the plugs. Ford says they are good for 1000,000 miles. LOL if you go that long without changing them they become part of the cyl. Head. Most of them have to be broken to get them out. This is no fun at all. There are special tools needed to do this. Ford actually makes and sells the tool kit but denies the problem totally. Go figure. Check it out on you tube. I have done 3 of these trucks and boy did it suck. 6 of the 8 plugs broke.