I'm curious why it's an either-or situation. Why not use both? If you compost them, the result is likely to be close to neutral either way. Unless the spent grains are really out of whack for pH, I don't think they'll change the pH much if used directly. There are probably differences between the two. If I had access to spent brewing grains, I'd use them.

The worse beers are the low grade malt liquors and cheaper canned beers found in most grocery stores . Also light beers are really just malt beverages designed for people who don't really like beer . I would like to clear up the confusion on Corona . It is one of the highest quality commercial beers available . It is brewed with all malt and Noble hops imported from Europe such as Saaz , Hallertau or Tettnang . It is the most popular beer in Mexico and the recipe was brought by German settlers in northern Mexico . Most American beers are much lower quality and use garbage additives such as rice and corn syrup to cut cost and create a lighter watery color . These adjuncts are illegal in Bavaria and cause strong hangovers . The bright yellow color of Corona is because they don't add the headache ingredients . Most large breweries blend 20 different cheaper hops to create a consistent low grade flavor . Cheap malt liquors and other American beers will use scrap byproducts such as apples or potatoes instead of malted barley to cut costs . Here is a link that might be useful: Hop varieties

Useful story ... and a good one, too. As for the beer ... I'll take milk ... or coffee, if you don't mind: I think that someone should pay me to drink beer. They just brought six very large vats, built somewhere abroad, from Hamilton Harbour, at the west end of Lake Ontario, to a brewery near Toronto airport, arriving this morning about 4 a.m. They had to move about 150 light standards (I think - they referred to "traffic lights", but I think that they really meant the ones for illumination) ... and something like 1,500 wires had to be dealt with. ole joyful

Since you're not a beer lover yourself I think it would be a mistake to buy a microbrew or other obscure beer for this. I'd offer a nice, safe variety such as: Sam Adams Octoberfest - Seasonal, a bit darker. Stella - A popular/trendy/drinkable "regular" beer. Heineken Light - Personally I'd prefer Miller Lite, but I'd buy Heineken for appearance's sake.