I'm not sure if you had a chance to look around but there are a couple great threads with feedback about entry level flatbeds from the last couple of years.
We were just in the same boat...and I spent the good part of a year to make the decision.
We ended up going with the Oce Arizona 318gl and are extremely pleased with it after almost 3 months.
Couple of things I would pay attention to, besides the up front purchase price:
-Overall cost of ownership. ie: consumables, heads, lamps, service plan (expect to pay approximately 10% of the value of the printer, per year, for service)
-Access to support and service (how close is the dealer that sells you the unit and how helpful are they actually going to be when you have issues)
-Inkset: Most manufacturers offer choices when it comes to their inkset because just like vinyl, not every ink is good for every application. In Oce's case, they offer the 255, 256, 257(still being tested I believe) and 258. These inksets range from lower adhesion/higher color gamut to extremely good adhesion/lower color gamut. When making the decision we looked at the same image printed on 255/256/258 and you could really see a difference. So far 256 has adhered extremely well to just about anything we have thrown at it including lexan, glass, acrylic, mirror, fabric, paper, coroplast, styrene, sintra etc etc. The only issue we have encountered was with 10mm coroplast was an uneven finish and I believe it was related to a quality control issue with the coroplast.
So keep in mind what substrates you need to be able to print to, as well as new products you would like to start producing. Once you have one in your shop you'll think of all sorts of cool things to print on.
-Footprint: Depending on how much space you have, some models take up more room than others depending on their configuration. If considering a hybrid you need to keep in mind the feed tables and working area required to feed sheets through the printer. This doesn't apply as much with a true, moving gantry, flatbed, although you need some space around the unit to load sheets and perform maintenance.
-Regular maintenance: Each manufacturer handles maintenance a little differently. A lot of them have automated maintenance to take the "nuisance" out of it for the operator. Personally I don't like this philosophy which is why I just threw out my HP desktop printer. I don't like equipment that cleans itself all the time because you aren't in control as much. In oce's case there is a daily/weekly/monthly/etc maintenance schedule which must be performed by the operator. I was originally a little turned off by having to manually vacuum the heads and clean the plates every morning at first but it takes less than 5 minutes from start to finish.
-Updatability: Certain manufacturers have x amount of room for additional heads, depending on the configuration.. usually this allows you to add more heads (for around $10k each) down the road if you find you need more horsepower or want to add more channels. Some manufacturers offer this, some don't.
-Roll to roll option: Another reason we went with the Oce, is the configuration of the roll option. It is a completely separate unit that is installed on the front of the printer and can be added after installation. It can be loaded up while the flatbed is in use so that your time to switch over is as short as possible. We opted to wait on this part as it does add quite a bit of cost and we wanted to determine how much we would really need it before jumping the gun. After just a couple of months I already know we would use it almost every day if we had it installed. The configuration of the printer will also dictate the how wide the roll to roll option will allow you to print. I know on some of the units (mostly hybrids) it is around 64" or so.... which to me isn't that beneficial if you have 54" or 64" solvent printers as well. I believe the Oce roll to roll has a max width of 86" or so which in our case would be wide enough - we rarely have a use for larger banners than that.
I'm sure I'm forgetting other things to consider but those are the first things that come to mind.
Out the units you mentioned I only have experience with the Oce, and the others weren't on my list when we started shopping. We looked into the the HP FB500, AGFA's, CET's and found the Oce to have the best quality prints at the best price point. The white ink option is also worth considering - we knew beforehand we would get this option and it has been a great decision. The white is nice and opaque and you can create some amazing prints on dark or clear substrates. Keep in mind you need to run jobs daily with the white (or just print blocks of white to keep heads firing) as the white head will clog much more than the others. This is likely going to be the case with any printer white ink due to the chemistry of the ink... and the pigment separating from the carrier etc etc.
In terms of print speed....the 318gl is not a speed demon by any stretch of the imagination. Running 4x8's of coroplast or dibond on production I believe we can get about 4 an hour. There is a faster setting that that one and the quality is still okay, but I'd rather tie up the printer for a couple of more minutes to have a nicer finished product for our customers. Printing white using a spot/spot/color quick set........you're looking at about an hour per 4x8. This does tie up the machine more than I'd like but keep in mind not a lot of people go for the white option (around here anyways) so you need to charge what's it worth.
So that's my (somewhat biased) advice. I could probably go on all day about this as it's still fresh in my mind, but I have work to do! Any specific questions just let me know, I've got lots of Oce related documents I could pass along.
