I'd go with ALDI Talk, because ALDI is ubiquitous and the card also offers cheap national calls (14 cents, and 4 cents between ALDI Talk users, if you're travelling in a group), and most importantly for data, UMTS access.
Alternatively, Blau is available at electronic stores like Saturn and Media Markt and has the same data rate (though national and Blau-to-Blau calls are slightly more, at 16 and 6 cents), but no UMTS.
International calls are, unfortunately, a ripoff with both Blau and Aldi Talk (2 euros per minute) and you will want Blauworld for that (9 cents/min to Canada); you can get it at the same places regular Blau SIMs are for sale (however, Blauworld has expensive data, sigh.)
There are no different settings for UMTS; they are the same as GSM, although you will obviously need an UMTS phone. The APN is wap.eplus.de - there's no reall difference in settings between E-Plus offers (which is what Blau, Simyo, ALDI Talk, etc. are).
From
http://daten-tarife-vergleich.com:
Konfiguration Eplus WAP
* Primär IP: 212.023.097.009
* Primär Port:Wap1.x 9201/ Wap2.0 8080
* Datenträger: GPRS
* Access Point Name/APN: wap.eplus.de
* Benutzername/User: eplus
* Passwort: wap
* Startseite:
http://wap.eplus.de
Konfiguration Eplus GRPS
* Primär IP: 212.023.097.002
* Primär Port: 8080
* Abbruchzeit: 180 Sekunden
* Datenträger: GPRS
* Access Point Name/APN: Internet.eplus.de
* Benutzername/User: eplus
* Passwort: (leer)
* Startseite:
http://www.eplus.de
Konfiguration Eplus für Modem oder Laptop Karte
* Netz: E-Plus
* Access Point Name/APN/Zugangsknoten: internet.eplus.de
* Erster DNS/Primary DNS: 212.023.097.002
* Zweiter DNS/Secondary DNS: 212.023.097.003
* Benutzername: eplus
* Kennwort: eplus (leer)
* Einwahlnummer: *99***1# oder *99# oder *98*1#
* IP-Adresse: dynamisch
* IP-Header-Komprimierung: nein
* Protokolltyp: PAP
AT-Befehle für manuelle Modemkonfiguration: AT+CGQREQ=1,2,4,3,9,31 / AT+CGDCONT=1, “IP”, “internet.eplus.de”