Which Neo Geo?

CD can play backups right? Plus originals are cheaper, I believe. But CDs load a lot slower.

Don't have either, but please correct me if I'm wrong
Well, they all have their pros and cons. Here's a breakdown.

NeoGeo CD/CDZ - can play Backups, games are pretty cheap. Load times are unbearable. Close to 60 seconds for ONE MATCH in King of FIghters 98. (thats IN BETWEEN ROUNDS TOO) To me, not worth it.

NeoGeo MVS (arcade) Most bang for buck, for older games. KOF98 can be found for as little as 25 bucks, while new games, like Rage of Dragons/KOF 2001 can run about $700 to $900. Great for getting older hard to find games. Bulky. Decent value. Games decrease in value rather quickly.

NeoGeo AES (Home Cartridge System) - Best Value. Games are evenly priced, older ones (Magician Lord, Samurai Shodown 1, etc) are in the 30s, to 50s. New games, can go as high as 400+, more if they are in limited issue.. which 99% of them are. Games increase in value over time. Metal Slug 1 can be over $1500. KOF94 can still fetch over $100. Carts are prettier, have casing, manuals, etc. Nice for a collector. Irrelavent for a gamer. (they are irrelavent to me)

Hope this helps.
money makes the difference, get Home carts if you got lots of cash, get mvs if you want carts but noo poor for home carts, get cds if you cant afford the mvs carts. carts have no loading times, where the cd loading is annoying as hell!! cdz is tolarable but barely....and cdz is japanese only. you need to use cracks on some cds to work on the home cd and cdz systems....
And keep in mind you will need an arcade cabinet for MVS as well which adds another buttload of cash depending on how nice it is.

AES CAN play MVS games with an adapter but those cost alot too.

Get the CD system if you can live with the loadtimes and a lack of some games (especially newer ones).
plus the cd system has tons of things completely removed from the games to save time on loading, I own them all and the cd system of neo-geo is truely kinda a sad situation.....its the closest thing to the cart. but, not 100% the same at all. If you want the REAL dael, get the AES home carts. But good luck if you are poor, games like Metal Slug 1, Blazing Star, Pulstar, Ninja Masters...etc... will cost between $700 up to $1,500 bucks...
Neo-Geo carts have always been expensive since day one. They weren't made in terribly large quantities and some games (like Viewpoint I think) were made in limited numbers. Growing up as a kid I could only dream about affording a Neo-Geo console.
I only thank god I was able to grow up owning all the neo-geo carts....life can be grand.
The most Neo Carts ive ever had was 10. Mostly older games like Magician Lord, Crossed Swords, etc. But I did have KOF 95 and 98, (got them BOTH for 80 bucks.. TOTAL) and Windjammers. One of THE coolest 2 player Neo Games ever.

Ive had 3 AES systems, a full size MVS, (single slot), and a NeoCD for about a week. Hated it.
you sound like me, I bought 3 aes systems as well, (I had to replace one after another when I was testing them out with a metal screwdriver in diff. spots) and same here I bought the MVS full machine as well, and both single speed and double speed neo-geo cds. I am an SNK freak! even got a huge tattoo of Haomarou on my forearm covered in blood and my plate on my car is SNK 4ME (hey I live in CA. and ALL the other stuff with SNK was allready taken) plus I have a massive SNK collection including Art work books, movies/anime' , music, clocks, ink pens, buttons and about anything else that has SNK printed on it. I cant wait till I get a water paint type of tattoo covering my entire back of Nakaruru and her bird with a waterfall in the background.
well, you dont need a cabinent for a MVS if you build/buy a supergun. and the reason the carts cost so much is tha tthey are huge amounts of memory, its like buying a ton of ram.
I always found the NeoGeo CD system load times quite bearable.

Even in KOF98. It was 60 secs for a match load but about 15-20 for rounds. Really, it wasn't any worse than the PSX version of KOF98.

KOF99 and Last Blade 2 howver were totally unacceptable. Other than those however, I found the machine quite good.

And yes, some things are removed from games. For example, Ryuuko no Ken Gaiden on the CD system removed the zooming effects in the arcade game. I was a bit pissed about that given how much they put together for the box set (the poster, the coin, etc). But the phenominal arranged music made up for the lack of zooming.
I always found the Cd laoding times bearable as well. The only ones I really can't stand because of loading times are Last Blade 2, KOF99 and maybe Samurai Showdown RPG.

On the bright they did improve Magicain Lord when it ported to cd format. They made it when you die you start back right where you died instead of having to play through part or the entire level again.
metal slug 2 is unbearable as well, hell loading 3 or 4 times per level sucks badly.....no wonder the other metal slugs had no chance of seeing thier way to the cd system, loading would take forever. loading on the neo geo cd special is very tedious also..... it loads and loads and loads.... I wont even mention ADK World.... yikes...

Oh and yes Magician Lord is more like the arcade version on the CD than the home cart, but the music is horrible , its like they did viewpoint, the music was taken straight from the cart and downsampled to mono or something, it sounds like shit! Plus some of the music sounds arent even there making me think they just took the music from the left sound channel of the carts before they downsampled the music.... it sounds really bad compared to the cart. then you get some games like Aero Fighters 2 and the music is totally redone and sounds awesome CD Quality, then I got Aero Fighters 3 and found they took the music from the cart as well and threw it on the cd instead of redoing it to sound good.