Don't know if this quite counts, but I do prefer the emulated version of Battle Garegga over the Saturn version...visually. The lag screws up the MAME version though.
I like the graphic filters in MAME, and I think it helps certain games.
I buy shit because I play mostly Konami games... and Konami games suffer from Horrible emulation. Gokujyou Parodius is still far from being emulated properly, owning the real board has been huge for me. Same goes for Sexy Parodius, which is even worse. Gradius IV (not that I can play it while my board is broken -_-) is a complete crapshoot in mame even if you've got a beefcake PC. Before I had the availability of Gokujyou Parodius (As I was trying to buy the board BEFORE I even owned a cab, it just turned out that It became widely available about 3 months after I bought my cab) I would play it in Mame for Hours and be happy, but now I can't even double click on it because the graphical differences mean so much to me (because EVERY transparency is broken in Mame on Gokujyou Parodius) and the sound quality isn't anywhere NEAR a real stereo amp connected to a Konami GX.
While I can't afford everything I want (As a fucking BS Gradius shows up from time to time, at a price point of 1000+ USD each time) I can turn to emulation when I don't have/can't get/refuse to invest in broken hardware (Xexex. Haven't heard of ONE yet that doesn't blow capacitors every few months. Won't buy one on that alone) and be reasonably happy, however I do try to own the real thing when I have the chance.
I emulate everything. The only exception is putting a quarter in a machine in an actual arcade. Personal collections feel like unnecessary clutter to me. Just my opinion.
I much proffer playing the originals (though by originals I mean home ports for home consoles - not the boards)
These are the best compromise as they are more cost effective and storage/playing them is a whole lot easier. Problem I get is games like Progear and Guwange (O.K this one is incoming) which are not available on home consoles the only way I can play them is via MAME (other than owning the board) so for this reason MAME is a great way to play and experience games you wouldn't normally. Plus there are great conversions on there like Dodonpachi which is way better than the Saturn port. Lastly playing 3rd strike online is a dream so GGPO also has its place.
I tried playing Metal Slug 6 on a PSP, then tried it in a PS2 emulator. I could swear my score had doubled in the emulator, and this game doesn't even reset scores on continues!
Most of the time I play games through MAME or other emulators as all consoles these days would just be going through my LCD anyway.
I buy console shmups. Both arcade related and not. No PCBs as I simply don't want to deal with the expense and clutter of a PCB collection. I also don't usually buy Neo Geo AES/MVS carts but I made an exception for Pulstar and Blazing Star. Still most everything I play is emulated even if I own a physical copy of the game. It depends on the quality of the emulation or convenience as to what I play a shmup on.
The problem with collecting is that it just sits there looking at you. Its all very well thinking before you start that your going to own every DC, Saturn and PC engine shmup but what in fact your doing is just wasting your money.
If you want old games, just buy your favourite 5. If you buy a game and it ends up sitting on the shelf just get rid of it.
The only exception to this is nostalgia. IMO that actually means that back in the day you owned the games and you want them for memories sake. Usually only a few games fit into this category though.
I have about 200 games. 180 of them will never be played again. Either because im bored of them, bought them on impulse or just can't be bothered with them anymore. I actually own a Cave kit that i've never plugged in. EVER! I've got a Cyvern PCB sitting somewhere that I have not even plugged in. I know I'm terrible.
The problem with emulation is that your at the mercy of what is emulated and how good that emulation is. It is free though.
This industry has become 2 dimensional as it transcended into a 3D world.
I suppose a good plus point with with emulation is that you can use whatever controller you want and map it in any way you want too. I remember hearing that the DC pad can be a pain to use and that some games were mapped to the pad in wierd ways, emulation solves that.