You're smart to get bagless over bagged. If you MUST have one of these (to be honest I'd rather have a used quality product than a cheap new one (maybe Panisonic or Sanitaire, you could probably get a new low end Panisonic for a similar price), I'd say to go with the Eureka.

Here are a few reasons why... this isn't organized... just ramblings as I compare the two mentally.

I used to sell these Eurekas at Sears when I worked for them and the Hoover version as well. The Eureka is heavy, and the attachments fall off. BUT... the Eureka is MUCH quieter, and I feel more solidly built. The Hoover has a little more aggressive agitation, but the Eureka is sufficient. The Euereka has a more comfortable handle (providing the seam where each half of the handle meets doesn't protrude and cut into your hand, I've seen some that are like that)... it is contoured instead of straight like the Hoover. The Eurekas's height adjustment is easier to use... the Hoover takes more force. The Eureka's hose is much better quailty, though more narrow than the Hoover's thin plastic hose. The Eureka requires you to turn a valve to switch from carpet to attachments, the Hoover you just pick the hose up and suction will be there. That's not a bad thing, just a matter of fact. The switch on the Eureka is a little easier to get to (it's a little higher up). The Eureka gives the ability to turn the brush roll off for bare floors (which may not matter for you since you need it for carpet. This isn't to say the Eureka is good and that all Hoover's are bad (stuff made before the 90's is good), but in this case, this specific Eureka is much better than this specific Eureka. I think the Eureka even won best buy in Consumer's Report... not that that means anything, sometimes their opinions are dreadful, and possibly purchased!

I just bought a Hoover Tempo yesterday and couldn't be happier- $75 at Best Buy and it works great! Absolutely powers through pet hair and anything else. The attachment hose is short, but that's the only complaint, and really isn't a big deal. I always buy inexpensive Hoovers, usually get 3-5 years out of them. With this thing, I honestly for the life of me cannot understand why anyone would buy an expensive vacuum. It is outrageously powerful. Looks kind of cheap,(even the lettering is kind of cheesy as I remember) and the Eureka probably is better built, but it's pretty light (I picked it up to reach the ceiling with no problem) and really, you're not going to crash the thing around. I would recommend checking out reviews to see if you can get an idea of its lifespan. Still, an amazing vacuum!

I have looked at both of these when helping a friend decide on what to buy, I believe both were highly rated by CR. I believe part of the decision would be based on your needs (carpet, tile or both) THe feature on the Eureka that allows you to shut off the roller for doing tile is nice. On carpet I believe the Hoover is a better cleaner and probably more durable. I dont like the belt on the 4870 at all, looks like it would slip even when new. Repairs are more frequent on this model as well, or so I was told by a reputable vac shop.
And I couldnt agree more on CR, their opinions are sometimes dreadful and I would never purchase anything based on their reports

Consumer's Guide has given Eureka vacs as one of their top recommended value vacs for quite some time. I have two & for the cost I am well pleased. My son has a Kirby but he comes & borrows my Eureka instead !!

Vacuumfreak, why would you suggest that Consumer's Reports opinions are purchased? They take NO advertising at all. What do you base this opinion on?

happyladi... I just have to wonder at some of their vacuum ratings... sometimes they rate GREAT vacuum slow and terrible vacuums high. I guess I'm the ultimate conspiracy therorists... LOL In truth, there is no hardcore fact behind that statement.

Duajones... I think you're right in that the Hoover has more aggressive agitation on carpet (though it might be too aggressive for some carpets)... I think the Eureka would be adequate though.

I have the Eureka SmartVac, and purchased it 3 years ago. I had a Panasonic vacuum previously. When I first got the SmartVac (same model you are looking at), I thought it was doing a good job. It came installed with the vacuum bag as it was the last one at Best Buy and was the display model. I decided to check the bag to see how full it was, and in just 2 months of use, the bag was completely full, in fact, way overfull. That's when I realized just how much it picked up. With the Panasonic, I only had to change the bag twice a year. That's how little that vacuum picked up. I have a cat and a dog, with a gas forced hot air heating system that kicks out lots of dust. The SmartVac does an excellent job on carpeting, but is not very good on my hardwood floors. Yes, it can be adjusted for the floors, but I would give it a 'C' rating for how it does on the wood floors. I would give it an 'A' for how well it does on carpeting. In addition, it is extremely heavy to carry up and down the stairs. It's not hard at all to vacuum with it, but dragging it upstairs to do the guest rooms is not easy.
I paid around $140 for it on sale, and generally am pleased with it, other than the negatives I mentioned.

The Eureka and the Hoover have the same aggressive agitation. The Hoover is going to be a basic, no frills Hoover upright.

The belt, on the Eureka, is not a cheap belt. It will last quite a bit longer than the Hoover. These are Eureka's extended belts, so you will not have to change them every year.

The Eureka is heavier than the Hoover. Eureka also has a heavier handle-weight. This means that the handle will feel heavier while you hold and push the vacuum around the carpeting.

If you are going to use the hose more often, you might want the Eureka. The hose is longer and more manageable.

The Eureka is going to be quieter than the Hoover.

Try them out and see which one you prefer.