Valkyries look very f2p friendly, their searcher is a R, the UR isn't even necessary and you definitely wouldn't want more that 2 copies of the high level SR in your deck.
You can use a skill that gives you a field spell to summon the big Valkyrie instantly.
Some people want to run them with Valhalla but there's a card in the card trader that does kind of the same and it is a quick play spell.
We will have to see, in my opinion they'll at least be at d/d level, not tiered but good for the ladder.
They can swarm easily so you can use plasma, they get high level monsters without using your normal summon so you can use some tuners there.