He asked for popular, not available.
The number one no doubt are the AP units.
The Dräger had a good run, and a boost a few years back due to NRC heavily promoting them in Germany, as well as Austria and Switzerland. These days though support for most part seems to come from W+S Watersafety and TecMe rather than Dräger or Aqualung.
The Jetsam Classic Kiss has been quite popular, too, Kim Smith told me she's been selling more of them to Europe than in North America.
The rEvo as mentioned has developed quite a following very quickly and is worth a close look.
There have been quite a few Megs sold to Europe, too, and support seems to be okay. IIRC, it's out of Norway.
Everything else seems local and/or limited. pSCRs have been popular with European cavers, and you'll find the odd MK series, Cis-Lunar, PRISM etc in Europe.
The Ouroboros has sold reasonably well given the rather steep price tag, so the upcoming Sentinel (March 2008) should do better. Prices are between 4500 and 5400 GBP.
Jordi Mateo is a member here, based in Spain, and a good person to contact.