Malt

There are many malting companies out there to choose from. I have a preference for higher end English malts and for higher quality German malts. I have also used Belgian and Canadien malts with great success. Much of this comes with experience and talking with respected pros that have already done batches with various similar malts. Usually the higher quality malts are more expensive, so not used by microbreweries as often.
It is common for US micros to use Briess malts as Briess is a US malt house, making shipping cheaper on many occasions, and does not need to be imported. I have not liked this malt (generally) as it has a distinct flavor that to me that is slightly acidic, and grows tired on the palate as a beer is consumed. This sticks out like a sore thumb when producing more delicate styles, especially lagers.

The Crush:  There is one aspect of all grain brewing that cannot be over looked. Having grain pre-crushed by professionals is a good idea, but when buying grain by the 55 lb sack it may not be possible. There are malt mills available that can be purchased on line or at the shop, but I recommend the purchase of one that can be adjusted. The objective is to be able to break open every kernel without pulverizing the husk into powder. The husk is important as it is the basis for the grain bed and allows for the sugars to be rinsed out without a gooey sticky mess forming and causing a stuck run off. Under crushing on the other hand will result in a reduced efficiency. Take a look at the crushed grains being used. It should be observed that all the kernels are cracked, with husk intact and a mix of powder and starch chunks present.

Malt Mill

The old malt mill that we use for crushing grain

Malt mills are available through the local shop or can be found on line. Maybe not this particular model though because it is nearly 20 years old....
Crushed grain

Properly crushed grain is important for mash efficiency.

Some freshly crushed grain.
My objective when making a homebrew is to make beer that is craved by the drinker. I like my beer to make me want more. The first step in this process is finding malts that give the best results for the brewer and the beer style. I am not going to say that everyone will get the same results as brewing systems vary, and everyone's taste is different. This is where a homebrewer has the advantage of brewing 5 gallon batches and experimenting. Use a different malt for each basic batch and see what tastes best. Listen to experienced homebrewers and pros to get a starting point. Many of my suggestions are in the recipes that I have posted here. 
Below is a list of base malts that I have used and any notes worth mentioning.

Avangard Munich Malt (Germany)- Used this with decent success. Increased yield and lower price is a big plus and malt flavor is very good. Had a 21.5 Plato OG using 16 lbs of malt for a Doppelbock.

Avandard Pilsen Malt (Germany)-  Smaller kernels, needed to adjust rollers for a better crush. Yield is greater than with other malts that I have used. I have hit 14 Plato with 9 lbs of grain, and 18 plato with 13 lbs, to give an idea. Malt flavor is very good, and has the German Lager quality for which I am looking. Sack currently runs $60 at my local shop.

Briess Malt (US)- I most recently used Munich in a Dunkles Lager and partially in a Doppelbock. I did not like the flavor it produced. I have been told to avoid this malt so I have not used this malt much. Picking out what breweries use this malt can be an aquired talent. Blue Point toasted lager is an American lager that uses this malt and has its distinct flavor.

Canada Malting CMC 2 Row-Neill Acer recommended us trying this malt, as he was using it at the time for his brews. We bought it off of him. The beers we made had en excellent malt character. This was used for our Ales at the time (Pale, IPA, Porter, Stout, Barleywine, Imperial Stout). Not as dark as a Maris Otter malt but very flavorful.

Canada Malting CMC Superior Pilsen-Another malt purchased through Defiant Brewing. This was used one year during lager season with good results. We used decoctions in the mash process and had no issues.

Castle Malting (Belgium)-Have purchased Pale Malt and Pilsner malt from Neill at Defiant and used them with success. Very good quality malts and highly recommended.

Crisp Maris Otter Malt (UK)-Readily available, this malt is an excellent base malt. Rich malt flavors eliminate need for specialty grains in most cases. Great for all ale styles, I even like it in American Beers.

Crisp Pale Ale Malt (UK)-This malt is a little less assertive than Marris Otter, but is an excellent base malt.

Crisp Malting, Gleneagle Maris Otter (UK)-This malt is a step up from Crips basic Maris Otter. If you can find it, give it a try. We used this for a time in all our ales with outstanding results.

Durst Pilsen Malt (Germany)- It has been a while, but this is a quality malt that I can recommend for German Lagers. Have not seen this one around recently though. I used this back when Greg Zacardi of Ramstien (High Point Wheat Beer company) was using it for a time. Did decoctions while using this malt and it worked well.

Durst Munich malt (Germany)-Have used both the Light Munich and Dark. The darker Munich imparts a nice red color, but do not have a grain bill of more than 30% for the dark. Used these making dunkel and doppelbock with great success (and using decoctions).

Muntons Maris Otter (UK)-A step below the Crisp in character. We used this malt when we first started doing mashes. It is not bad, and better than Briess, but does not have the character that Crisp, Thomas Fawcett, or other UK maris otters have.

Muntons Pale Ale Malt (UK)- -Again, better than cheap American base malt, but not up there in quality with the better UK, Canadien, German, and even Belgian malts.

Thomas Fawcett Maris Otter (UK)- Used this one recently in several ales and loved the complex character and deep carmel color. Definitely a malt to be used when looking to have a great malt backbone to balance out hops.

Weyerman Pilsen Malt (Germany)-Have used this off and on for years. A very good malt for making German Lagers or even Belgian Ales. Have used with Decoction mashing and been happy with the results.

Weyerman Floor Malted Bohemian Pilsen Malt (Germany)-This takes malt character to the next level. Have noticed some similarities with the malt character of smaller German Breweries. Makes an excellent Pils, Helles, or Maibock. A bit expensive.

Weyerman Floor Malted Dark Malt (Germany)-Got my hands on a sack of this in 2012. Not as dark as I thought it would be. Too light for Dunkel. Nice rich flavor, but color was more like an Ofest. Made a tasty bock beer though. This malt is more like a Vienna than a Munich. Decoctions were used with excellent results.

Weyerman Munich Malt (Germany)- Great for making Dunkel and Doppelbock. As of December 2013, I have both of those going right now, with 100% Munich as the grain bill. Decoctions used with excellent results.

Weyerman Pale Ale Malt (Germany)-Have used this in the past with good results, though it was a long time ago. Give it a try if you can find it.

I highly doubt that this list is complete, and I will add more to it as time goes on. I have used a Czech undermodified malt a couple of times a while back, doing decoctions, as a pilsener malt but I do not remember the brand or even if it is still available. Also Neill Acer gave us a sack of what he called the "Best Malt in the World" but wouldn't tell us the name, though it was expensive and was a Maris Otter malt. Made 5 outstanding batches of brew with it and loved every drop.
Crushed Grain Texture
Closeup pic of crushed grain