It is often in the progression of your Minecraft adventures that you will begin with the simple farms, eventually moving to cactus and sugarcane. Farther on, provided you get far enough , you will inevitably look upon spawners as powerful mechanisms for farming xp, status symbols of success and money making machines. Before you go off to get your first spider spawner however, its important to look into which spawners are best for you and how to use them.

Getting To Know Your Spawners
1. Chicken Spawner 1/9 rating
Chicken spawners  are one of the cheapest spawners, and therefore easiest to get your hands on however they can be hard to farm as these spawners require grass blocks nearby for chickens to spawn. If you want to Automate a chicken grinder water timers need to be used.

Animals spawn on the water, are pushed into the hole and killed. Combine your animals!

System where animals spawned, pushed into a one by one hole by water after which the water later stops.
When all is said and done chicken spawners will give you access to a reasonable food source in the form of cooked chicken, feathers, low money and eggs*. Egg farms also fairly complex, as chickens like all farm animals will freeze after some time, not dropping eggs anymore. To effectively farm eggs you need to automate a system which spawns them, moves them, and later kills them.

This farm design works by pushing chicken into the 1by1

2. Pig Spawner 4/9 rating
Pig spawners are also fairly common and cheap, but just like chickens require grass blocks nearby and a water timer to grind effectively. For your efforts though you will get mediocre money but an excellent food source, you likely wont have to worry about food with a pig spawner. (See Img.1)
An interesting strategy you can employ with pig spawners is using a chanelling trident or lightning activating sword enchant to create a mock pigman farm for gold, rotten flesh and gold weapons.

Gold farms can also be made in the nether, but you cant claim it and there is no guarantee it'll stay!

3. Cow Spawner 3/10
Cow spawners are slightly more expensive and rare than other animal spawners, but much like them still require grass and a water timer to use. These are more expensive due to offering an excellent food source just like pigs, but also giving a incredibly practical resource in leather. Leather is used to create enchantment books, item frames and dyed armor.

Img 4

4. Zombie Spawner 7/9
Zombie spawners are one of the most reliable spawners, offering the widest array of loot and being useful for many reasons. They are fairly expensive, but easy to use as they will spawn in the air and on the ground provided the area has a light level of zero (darkness).

Complete Darkness

Having a zombie grinder will provide you with a reasonable xp source, moderate money and loot ranging from rotten flesh, potatoes, carrots, iron, leather - diamond armor as well as weapons and tools. Additionally you can attach a drowning tank to your zombie grinder to make it into a drowned farm, which, depending on your versions, will give you copper ingots, nautilus shells and fishing rods. (Tridents can't be gotten from converted drowned).

5. Skeleton Spawner 6/9
Skeleton spawners are equally common as zombie spawners, though are slightly less applicable. Much like zombies they are easy to use as they will spawn in the air and on the ground provided the area has a light level of zero (darkness). Skeleton grinders will get you loot in the form of bones, arrows, bows and leather-diamond armor. Skeletons net slightly less xp than zombies on average.

Complete Darkness

6. Creeper Spawner 5/9
Creeper spawners are one of the rarer spawners, and expensive; Though they have limited usage. Just like both zombies and skeletons creepers require a simple monster grinder in a 0 light level. The xp gain from creepers is lower than both zombies and skeletons on average. They also only give one resource (though this resource is helpful) in the form of gunpowder; which is used to make fireworks and TNT.

Another form of a creeper farm (combine with spawners for best results!)

Creepers do have two other uses, though difficult to employ. One is music discs, which require a skeleton to kill the creeper in your grinder. The other is using channeling or a lightning effect sword to create charged creepers and farm mob/player skulls. Music discs have no real use however, and beheading is a more effective way of gathering skulls - which have very limited usage.

Many music discs can be farmed this way - and are nice to add to your collection of rare items!

7. Spider Spawner 2/9
Spider spawners are slightly more common and less expensive than other monster spawners, but significantly less useful as well. Spider spawners function the same as other monster grinders in light, but due to spiders being 2 by 2 wide - they are more difficult to create collection pits for. They can also climb walls meaning proper effort and complex farms are needed. Spiders drop string and spider eyes, and are equal to creepers in xp gain.

Spawners from dungeons and mineshafts are not usable-always give them to staff to be removed 

8. Blaze Spawner 8/9
The second best spawner in my opinion, blaze spawners are not very versatile but quite efficient at what they do. Blazes can spawn midair and in any light level below 12 and can easily be moved by water. They produce good money but where they shine is in their xp gain. Blazes give the most xp out of the spawners, making them very helpful to have.

Its best to combine your high xp spawners for the best grinder!

9. Iron Golem Spawner 9/9
Iron Golem spawners take the top spot as the most impactful spawner, despite their rareness and price iron golem spawners (Or IGS) are incredibly strong. Iron golems spawn on any surface block with enough space, including in water streams. They do not give any experience and only have two drops, poppies and iron. Poppies aren't very helpful, but provide endless supplies of red dye and are certainly not useless, however the real bang comes in the iron. Iron is very valuable, both monetarily and  in versatility. Iron will provide you will an amazing money source, and can also be used for anvils, beacons, armor, pistons, tools and so much more.

My simple and expandable design for an iron golem farm

That concludes my explanation and rating of all of the spawners you can obtain in Blocklands fairly, if you have any comments or recommendations I would love to hear them.