I don't consider the Wizard's Grimoire to be a good book. It's full of unbalance mechanics and some bad ideas. It also has some good ideas and materials, but overall I won't recommend it (especially if you're short on money/time).
I likewise find the (4e) Medieval Bestiary rather bland. I won't really recommend it either.
I would strongly recommend purchasing the 5e books. They're great. Why are you centered on 4e books?
At any rate, the answer by book:
The Wizard's Grimoire, Revised: Mostly crunch that's not fitting with 5e, not compatible nor desirable for a 5e game methinks.
Houses of Hermes: Servicable for a 5e game, but the 5e House books are far superior and somewhat different (so if you'll use HoH you'll be playing in a non-canonical and worse game).
Mythic Europe: Don't own it.
Faeries, Revised: Although the stats will need conversion, and most of the rules probably too, it provides a fair amount of faeries and a vibe for what faerie is that's still very much usable with 5e (despite the great change in what faeries are in 5e). I didn't much like it, however. I thought it was overly filled with bad prose, not dense enough with ideas and material, and lacking and limited as a bestiary.
Hedge Magic: The book can provide ideas on hedge traditions, but I didn't particularly like most of the ideas there. I suspect conversion to 5e would be relatively easy, however (not sure, been a while since I've read it).
Ordo Nobilis: I just didn't like this book period, but it's perfectly suitable for a 5e game. If you want a book about noble's history, and for some reason don't prefer to buy an actual history book, you can get this.
The Mysteries: Although this version provides a little more fluff and flavor of the magical traditions, and was great, I would recommend getting The Mysteries Revised Edition for 5e. It's far more suited for a 5e game.
The Medieval Bestiary: I found it bland and dry. The statistics would also need a lot of conversion, which doesn't make much sense. I would recommend getting the 5e Mystery Cults and downloading the Book of Mundane Beasts instead - that gets you much of the content. You can gleam lots of ideas on magical beasts and animal-related symbolism and magic from this book, however, so perhaps you should consider it.
Living Lore: Don't have it, but I suspect it's pretty applicable to 5e (although mechanical covnersions would be needed).
Faerie Stories: Likewise.
Kabbalah: If you want a primer to mythic Judaism, this is an excellent book. It doesn't seem likely to be relevant to a saga, however, and the mechanics would probably need an overhaul.
Ultima Thule:Don't own it.
Parma Fabula: Irrelevant.
Triamore: Don't own it.
A Medieval Tapestry: Don't own it.
The Mythic Seas: Don't own it.
Mistridge: Don't own it.
Mythic Places: Don't own it.
More Mythic Places: Some nice ideas. Need lots of conversion, but some nice ideas so well worth it for any edition IMHO.
The Medieval Handbook: Don't own it.
Pax Dei: Don't own it. I suspect the 5e The Divine is far superior.
The Maleficium: Don't own it. I suspect the 5e The Infernal is far superior.
Sanctuary of Ice: A reasonably good Tribunal book. Some details don't fit the 5e cannonical view of matters, but that can be skimmed. If the place and atmosphere appeal to you, I think that's a good choice. (I don't think we'll see any tribunal redone.)
Land of Fire & Ice: It's an interesting high-level ArM saga, off the beaten path. Converting it to 5e will require a lot of work, however, and some thinking too due to the change in what Realms mean. I don't know.
Blood and Sand: Don't own it.
Heirs to Merlin:Don't own it.
The Dragon and the Bear: A 4e tribunal I very much love, I think this would serve well for 5e (although you will need converting the pagan priests and hedge wizards). A lot of work in conversion, but a lot of good ideas and an interesting place IMO. (They botched the whole Mongol issue, though...)
Tribunals of Hermes: Iberia : Don't own it.
Tribunals of Hermes: Rome: I didn't find it particularly appealing, and also a rather small and crowded tribunal. But I think it's largely still usable.
Lion of the North: Don't own it.
Cause & Cure: Don't own it.
The Black Monks of Glastonbury: Don't own it.
The Return of the Stormrider: Don't own it.
Festival of the Damned: An interesting adventure. Will need pretty heavy conversion to serve for 5e, but I think it can be fudged into place and be fun.
The Fallen Angel: Didn't like it. I think it's pretty applicable to 5e though, as much as it is to 4e.
The Bishop's Staff : I think it's as workable for 5e as it is for 4e, although I don't remember how much conversion would be needed.