I have an oliver 550 and 8N ford. I love the oliver for the ease of handling, power, and pto that is independent whereas the ford isn't. When you push the clutch in on the ford, you lose the hydraulics until you engage the clutch again. Go for the Oliver 550 and you won't be sorry. In my humble opinion, you can't beat the 550 for the best utility tractor. read this article.
Yesterday's Tractors - Oliver 550 Purchaser Checklist