JJ is in possession of some mighty fine wines, so he can give the sukos suggestions... If you can get ahold of Chateu Royemount 11 under 40, buy it... as JJ can attest, I have an entire eurocave full of just that wine, AMAZING.
I buy wines on a QPR scale. My go to wines are capcanes peraj petite and tabor adamah merlot, these wines in terms of quality far surpassed their cost.
But Shabbat and chag etc the question is usually "how much better is the 30$ wine from the 25"
Its tricky to be honest and a lot has to do with how long will you cellar a wine, peraj habib will cost you over 40 but will cellar for 10 years.
Here are the wines i'm drinking and recommend:
Capcanes peraj petita as stated above, sadly I drank up all my 2012 wich should age fine till 2017, the 2013 is just now becoming approachable but pesach time will be much nicer
Tabor adamah merlot 2011, this wine as above is easily worth twice the price
Fourcas dupre, ideally 2010 but 2012 can be drunk with decanting
Netofa Tinto 11
Royemount 11
Shiloh Secret Reserve Merlot...2010 is sublime
Netofa Latour 2011
Herzog SR Cab Sav Napa 2012
covenant Red C
Capcanes peraj habib
Then of course the kings, Shirah and Hajdu... insane wines! Of course there are others, but these are what im drinking