keel, spring and other frameworks

hi keel-users

i'm looking around since a while to find a java-framework for 
programming webapps more easily.

until now, i'm using struts, but i'd like to focus on my app and don't 
like to build up a "framework" myself just to save things to a database 
or build a login-page and protect functions of my app.

on the other hand i don't want to have a giant monolithic block for 
things that need just 5 percent of it - modularity is therefore also a 
serious concern.

as a third main focus, i'm a java-beginner with some struts experience 
and would be happy about a learning curve, not a 
"vertical-learning-line" :-)

having these three main "features" in focus, i read articles about keel, 
appfuse and spring.

i like the philosophy of keel very much, but i had serious problems to 
start with it ("focus number three"-problem). most of all because i 
didn't see "the big picture" and lack of documentation (sorry guys; but 
the began pdf-file is a great step forward! go on with it!)

after this "crash" i looked at appfuse (but don't tried it hands-on yet) 
to "extend" struts with the components i need - and finally the 
appfuse-path was pointing to spring-framework.

long story, short question: can anybody outline the most important 
differences between these frameworks - or - is there anything else 
that's the best thing for somebody like me?

i'm some kind of confused what to use for my current webapp and need 
some advice. most of all i don't want to invest lots of time just to 
realize that i took the wrong framework...

thanks for your help and greetings
stefan