Several years back, I split a Sanctus Reach: Stormclaw box set with a Space Wolves player and got started on the Killa Kans. I immediately took a liking to these armored Ork walkers and started building my own shortly after from junk and spare parts. It seemed a proppa Orky way to go.
Looking back, I remain reasonably pleased with the paint job on these first models. It's a passable tabletop quality, and that's good enough for me, I think.
I also traded for a bunch of spare parts and collected a lot of suitable scrap to try making my own, as noted above. The first on the left here was far too small, but the other two seem close enough in size to satisfy me. The tiny one will still probably see use, but it is also very fragile. Maybe I can re-use some of the components for something else if it breaks too often.
Trading also got me 2-1/2 old metal Killa Kan models. These are goofier than the new plastic kits. I removed the too-small 40mm bases, stripped the paint with acetone, and tried building a replacement front body panel and weapon to complete the third. I am not entirely satisfied with the results, but this may be good enough. I should prime these and then rethink it if I still don't like it.
Lastly, here are some Kans that may be a bit too large, but these are too fun not to use anyway. The blue one uses a sphere from a vending machine dispenser, about the size of a ping-pong ball. The white model is a primed conversion of a poor-quality R2-D2 action figure. Once it's painted up, I may go over the build process in detail. And just for reference, one of the official models from the first picture is included, too.
Later on, perhaps I will show off some Deff Dreads. These larger cousins of Killa Kans also have neat official models and opportunities to build from scratch. The large kans above are still too small to be mistaken for Dreads, so I doubt anyone would object to their use in a friendly game. Some may even have enough Games Workshop parts to be considered tournament-legal, but I don't care for the hyper-competitive brand snobs who congregate there.
Warhammer 40K is so much fun, although it's entirely too expensive of a hobby for me to get into with as much other stuff as I play/collect. Fortunately I have friends who are huge 40K nuts, and allow me to occasionally pull up an army using their massive collections, and it's always a riot to mix up all the slap-dash technology and sheer numbers of models that Orks can field just to see what happens. The Killa Kans always make me laugh, but even their Dreadnaughts look pieced together with whatever they could find in somebody else's scrap heaps. :)
I like Kill Team because a much smaller investment of cash and time is needed to build a roster. But over time, and with some Orky ingenuity, I have slowly accumulated a fair heap of greenskins.
If I were to start playing, I could see myself putting together a truly obscene army of either Imperial Guard or Tyranids. Forget those peeps who demand quality over quantity...I want an army with so many models it bows the table in when I roll all those d6s on Overwatch. XD
Quantity has a special quality all on its own. That is also the appeal of the Ork Green Tide.
I have to admit a certain curiosity about elite armies like Imperial Knights and Custodian Guard, though. "All that overwatch tickled a bit. Now it's our turn!"
Oh, there's a morbid delight in watching somebody field an entire army that's made up of, like, five models that go straight into curb stomp mode, for sure! Really, a lot of the various factions lend themselves to throwing a whole mess of troops if you so desire: Eldar, Sisters of Battle, even Space Marines if you keep the Titans and Rhinos to a minimum.
Or at least this was the case back when I was more up-to-date on my edition lore. 4th, I think, was the last rule set I was familiar with, and I think they're up past 6th at this point, so take anything I have to say with a grain of salt. :)
8th ed. now. Sorta-kinda the same, but new hyper-elite armies have been added to the mix.
Guard blob is still top-tier. Nids and Orks are more variable. Soace Marines of various flavors are still solid, and the new Primaris marines get all the love nowadays, but the Classic Marines can pull their own weight just fine. Chaos has improved. Sisters of Battle are getting a re-release just now. Necrons are a bit stagnant, but they look cooler than ever. Tau still excell at shooting and become very squishy if you manage to close in.
New stuff:
Adeptus Mechanicus is really cool. Cyborg guard with radioactive guns and robotic support.
Imperial Knights are big stompy mechs with big guns. 4-5 models can make a 2000 point army. They can also ally with pretty much any Imperial faction in a combined arms strategy.
Custodian Guard are to Space Marines what Space Marines are to guardsmen. They uave a lot of armor, several wounds apiece, and they dish out the punishment like no one else. But they can be swarmed, and can have trouble controlling the board and capturing objectives. And they can take Sisters of Silence as allies to add numbers and deal with enemy psykers.
Genestealer Cults blend Imperial Guard nymbers and Tyrannid biology in scary ways.