While the Flavia machine had the advantage of a larger water reservoir and smaller packets, I think the Keurig has won me over. The water reservoir is not that big a deal, and supply storage isn't too big an issue. The convenience of being able to purchase locally for it is certainly nice, but what really made it easy to get used to is that it removes the two complaints I had with the Flavia machine.
First, the Flavia machine only did an automatic fill (press & release the button, have it do its thing) with a packet inserted. Thus anything that merely needed hot water (instant coffee, tea, hot chocolate) required one to hold the button down until it either stopped or one decided that there was enough hot water in the cup. While doing that, not much else could be done. The Keurig machine needs more than a button press (have to lift and lower the top as if feeding it a K-Cup, then press the button) but once done, the rest is automatic. I can now start things and not have to babysit the machine as I deal with whatever else.
Second, the Flavia machine had a short space for a cup. That was enough to be a bit annoying even with a slightly taller than average cup, and a proper mug was right out. The Keurig design will take a mug. That mug can be full of ice for iced coffee, or can have two K-cups worth of whatever. Probably marketing/design genius to be able to use twice as much feedstock easily. But that also means one less trip to the kitchen or a very easy mocha: a cup of hot chocolate and then the coffee - which works out as the coffee takes care of the recommended run after the hot chocolate without the fill being a waste.
There are a few refillable K-Cup designs, and evidently Keurig's own is the one people like the least. There are a few. I've seen good reviews of the Ekobrew, and was thinking about ordering one when I saw a Java-Jig at Wal-mart. The java Jig has a couple advantages: It's cheap and readily available, and doesn't require any special orientation like the Ekobrew or partial disassembly like the My K-Cup. (And it has a better name than 'My K-Cup'). The disadvantage is that it uses tiny coffee filters that I am not sure about any second source. They do make it less likely that ground end up in the cup and probably make cleaning easier. The real downside is that using it does mean losing some of convenience of the Keurig - just pop in a K-Cup and go. It's very clearly a cost vs. convenience tradeoff. Well, there is another aspect and that is that the limited (wide, but still limited) selection of K-Cup blends can be expanded upon.