How about neither... I'm a bit partial to the mighty Olympia Cremina. It's considered the Top Dawg among "home" levers for a reason. I acquired mine through alot of blood, sweat and tears.
Seriously, there's alot of info on the Pavonis, ask around/search over at Home-Barista. There are differences in those models, but I know little about them. They have their following as well.
Also, I understand Cremina parts are pretty hard to come by?
I'm sure the above reply meant to say that the La Pavoni Professional has a 16 cup capacity to the Europiccola's 8 cup capacity.
The Professional's pressurestat feature makes it a little better mannered than the Europiccola, which hisses quite a bit because there is always voltage going to the element when it is on. The older EP has a two or three position switch that gives a high and low wattage option (Off as a third option on the mid-late '70's design) that must be skillfully toggled at the right times to get the best results (or so it seems to me. "I" statements are very appropriate for something as manual & quirky as these machines).
I believe the later EP model is able to kep track of its own wattage/voltage, using a two position (on/off) switch. I've only messed with one of them, and it was a long time ago...
The ability to adjust the pressurestat of the Pro model is nice, and it's easy to do. It's capacity is also a plus. The grouphead of the EP and the Pro is the same. The gauge on the Pro is approximate at best.
The EP model (and to an extent the Pro model as well) has a tendency to overheat. I (I) drizzle just enough water over the group to where the machine stops hissing. This gives me a noticeably better result in the cup.
I've rebuilt a handful of them, and they're enough to keep you interested, while not being mind blowing to tear down and assemble again when you're done. Some of the switches and the rubber base of the older models are no longer available. My butane powered EP will debut sometime in the Fall...
I use two different Europiccolas regularly at my house and at my girlfriend's house. I love them, but they require more from the operator than any other machine that I know of. Good results are hard-won, but when you get good at it you are the F-ing MAN!