People seem to like the HOB refugium from Aquatraders. I have not personally used it so I can't really comment on how well it and the attached skimmer work. The other ones look like they could work OK but I would look/ask around in the equipment section before picking one.
The canister filter can be useful if you keep live rock rubble in it and/or keep carbon/filter floss in it. You need to be careful though because it can be a detritus trap and become a nitrate factory. I would skip it altogether and put that money into power heads for water movement.
I really do believe you would be best served by going with a small sump if it is at all possible. A 10 gallon with a budget skimmer in it from ebay would serve you much better than a cheap HOB skimmer/refugium. It's also nice being able to use a filter sock and keep your heater(s) out of the display. If you opted for a 20L sump you could easily do a refugium as well. Having the sump would also allow the micro bubbles you would be getting from a skimmer to dissipate before making it into the display. Those HOB units almost always have complaints of adding bubbles to the main tank. One last thing to consider is that as evaporation happens, if you don't have an auto top off your skimmer will stop working properly as the water level drops. In a sump the baffles can be setup to prevent this from happening and it will always be in the ideal depth of water. Again, I know you said you were going sumpless but I just wanted to give you some information to think about.
Here is
one similar to the one I have.
Also check out the WP25 from Jebao. I just got one and it has been working very well. No more dead spots in my tank.
