Hi, I'm a newbie, and this is my first thread (first post, actually). So please, everyone feel free to respond.
Hi from another newbie.
1. What do you think are among Beethoven's greatest achievements? Most "influential" works? Beethoven was the greatest composer of the Classical era
and the first Romantic composer! Who can beat that?
Most influentual works were - and I'm not very original here: his symphonies (the 3rd was a revolution and so was the 9th), his piano sonatas and his string quartets.
2. What are your favorite works by Beethoven?Impossible to give a limited answer: symphonies 3-5 and 7-9, middle and late piano sonatas, all string quartets, several piano trios, the violin sonatas, Missa solemnis, and yes:
Fidelio!
Least favorite?Some juvenelia
3. Do you feel that Beethoven's personal challenges (deafness; nephew issues; etc) considerably heightened the emotional content of his music?I generally think the relevance of these kinds of things is overrated.
So: no - emotional contect stems from character and intelligence.
4. Any favorite recordings? Of Symphonies? Piano Sonatas? Concertos? Chamber? Overtures?D Minor! What a question - please think of the workload in replying!

OK, some highlights (all of which are familiar favourites):
Symphonies: Jochum/RCO; Kletzki/CzPO, several Klemperer and Furtwängler recordings with the Furtw./9th with the Philharmonia from '54 as highlight.
Piano concertos: Kempff/Van Kempen; Solomon/Cluytens & Menges, Schnabel/Sargent
Piano sonatas: Kempff, Schnabel.
String quartets: Busch Quartet, Vegh Quartet.
Fidelio: Furtwängler live '53.
Q