you get approx 2 units in a pint and exactly 1 unit in 25ml of 40% spirit. Alcohol is a diuretic, which means that you'll need to go to the toilet a lot whatever you drink - beer is less damaging than neat spirits because it contains more water, which means you get less dehydrated, although you do still lose loads of electrolyte by weeing it all away. Admittedly, rate of alcohol absorption does peak at about 12-13% ABV - the strength of most wines or a well mixed sprirt and mixer in the ratio of approx 3:1 (i.e. the alcohol that's in your stomach gets into your bloodstream faster - at higher concentrations your stomach slows absorption because it recognises that it's a poison, and at lower concentrations there's less alcohol to absorb per unit area of stomach wall.) Faster absorption means you get drunk quickly, which is why wine seems to hit people a lot harder than most other drinks, meaning that you need less units of alcohol to reach that drunken stage, but it will wear off quicker than other drinks, but by the time you've drunk a bottle of wine, extra alcohol always seems like a good idea so that shouldn't be a problem anyway...
Hence Wine is the best and cheapest way to get drunk, but beer is a more sociable drink, and you can have beer without having to finish 10+ units worth of the stuff, unlike wine...