minimo you can't really have a favourite that you keep on buying, because they vary from year to year. And as others have said, it's a matter of personal taste.
I agree with Ann that Laithwaites are good, and you get a lot of information to help you make an informed choice.
One thing to bear in mind is that something like £3.70 (I think) of the cost of a bottle of wine is duty, so if you buy a bottle for £4.5O it is going to be very cheap wine. If you pay more the quality is going to be much better.
On the strength of an article in the Telegraph I decided to investigate Lidl and have been very pleasantly surprised and impressed. They have some unusual wines and they have a grading system (80 = good 90 =excellent) and the score of each wine is clearly displayed along with a booklet telling you more about each wine.
In fact we have just been enjoying a white Burgundy Saint-Bris ('a rare find for wine anoraks as this is the only example of a white Burgundy made from the Sauvignon grape') with a score of 88(very good) for £8.99. 
If you only drink one glass at a time it's worth investing in one of those vacuum thingies which will keep the wine drinkable for several days.
Enjoy experimenting
Our seas and beaches and climate change


. However, this plan is obviously flawed as I said because quite often I'll have a sip and be disappointed. Does anybody belong to a wine club? Or have a recommended wine that never disappoints? I think I might have to start taking this 'hobby' more seriously...