Hi guys, I have a final conclusion in my search for the perfect N64 display so I thought I'd share it here.
I've been collecting and evaluating displays for a while now and think I have found the answers I was looking for. This is only for the really discerning types who absolutely have to have the best N64 experience - most people won't even care and will be fine with what they have. Also this is all pretty pointless if you don't have your N64 RGB modded.
As I mentioned before, the high quality CRT monitors either have scanlines that are too prominent for the N64 or line double to make a blocky image. Also they are hard to find in 25 inches - the ideal size IMO. Go higher than 25 inches and the picture degrades significantly. Also any TV that frame doubles (100Hz) or line doubles (EDTV/HDTVs) will not do the N64 any favours. Old fashioned (preferably 4:3) 50Hz TVs are the way to go for the absolute best experience.
High quality shadow mask CRTs were virtually non-existent in the UK (apart from Bang & Olufsen, which have a horribly dim output). For us, the Sony Trinitron TV's (aperture grille) were the best of the bunch and produce an amazing, vibrant and sharp image. I've tried lots of other makes from the UK next to the Sony and absolutely none of them come close. This is partly due to the aperture grille technology they used.
The only downside is that Sonys are prone to the image softening and loss of clarity after a lot of use so it's important to get one that hasn't been overly used - ideally one that's been used in a guest room or bedroom instead of as a main TV. I've picked up a lot of Sonys and only one is really sharp - it had been rarely used. If searching on eBay etc. a good clue is how worn the remote is. The numbers wear away with a lot of use so a new looking remote is a good sign.
I wanted to also see if a very high quality shadow mask TV could surpass my Sony but this meant that I had to import from Germany. The Germans made a few brands that were the absolute pinnacle of shadow mask technology - namely Metz, Loewe etc. I decided to go with Loewe as they produced a few 50HZ models as late as the year 2000 while Metz stopped producing them quite early on.
After some research, the very best and last range of models they produced had the E3001 chassis - which has a reputation amongst CRT collectors as being very high quality. After shipping quite a few (5) to the UK, only one still had a really bright, sharp image. This is because although they retain their sharpness a little better than apperture grille TVs, they will lose brightness and contrast with a lot of use.
Although this was a time consuming and expensive process (not too much of a problem for me) I ended up with 2 absolutely brilliant low use TV's - one a shadow mask and one aperture grille. This meant that I could make a good comparison of how the N64 works with both technologies.
As I mentioned before, the only disadvantage to the Sonys are the slightly more prominent scanlines - which complement the 2D consoles but not so much the first gen 3D ones. This problem gets way worse on the larger sets - 29 inch etc. but the scanlines are much milder than that of an apperture grille monitor like the Sony PVM/BVM series - a favourite among retro gamers. Apart from that, and on a 25 inch screen, the N64 looks very sharp, defined, bright and colourful.
As for the Loewe it has an absolutely beautiful, clean sharp image. There is absolutely no colour bleed even at quite high contrast levels. The colours are amazing and as a whole this even slightly tops the Sony. The scanlines are much less prominent than the Sony but the side effect of feeding it a low resolution image like the N64's is that it looks a little 'bitty' in the horizontal plane and not quite as cohesive as the Sony as a result. It turns out that there is no way to feed a 240p image of a first generation 3D console to a really sharp display capable of displaying twice that resolution and not notice some kind of resulting effect.
Also, due to the intrinsically rough nature of the N64's video output (even if it's RGB modded), it will always look much better at a distance of 6 feet as opposed to 3-4 feet no matter how high the quality the display is. Actually, for SD CRT TV's the recommended viewing distance, even for 480i/480p content is 3-4 times the diagonal size of the screen so for a 25 inch screen this translates to a closest viewing distance of 6.25 feet.
Either way, at this distance, the prominent scanlines of the Sony and slightly 'bitty' image of the Loewe completely blend in to the picture and you have a really cohesive image. This, coupled with the fact that the 6 foot distance also negates the N64's rough output, gives a fantastic, sharp image - much better than a TV with a softer image. This is because you end up with the high clarity and sharpness of these TVs but without the imperfections of both the N64's output and the shadow mask/aperture grille - the ideal sweet spot for this console.
My conclusion was that I found that a really sharp, little used, high quality 25 inch CRT at 6 feet distance gives the absolute best picture I've seen from an N64 with the exception of using a quality CRT monitor at 640x480 (31Khz) with PC emulation using a custom VGA to scart cable (or an Arcadeforge UMSA adapter). The PC emulator settings have to be just right to get the perfect image. The Wii virtual console gives a fairly good N64 output as well but only the PAL Wii outputs in RGB Scart (s-video is not good quality wise) so for 60Hz gaming the only route here is using a component compatible CRT monitor/TV.
As you probably know, PC N64 emulation on a flatscreen just looks 'wrong' (i.e. not authentic) due to the low polygon count and other factors such as when 2D sprites are used as a 3D effect in 3D games (Mario 64, Mario kart 64 etc.) The Wii virtual console for the N64 also looks terrible on a flatscreen, even on a high quality plasma (i.e. more forgiving than LCD/LED for SD content). Maybe future Nintendo consoles can improve on this.
Personally I prefer to use the original N64 hardware though. The smaller you go with the CRT, the sharper the image is and the less obvious the drawbacks of the N64's output quality are. As I say, I prefer 25 inch. My N64 looks amazing on my 13 inch CRT but that's too small for me. A 21 inch might be a good compromise for some people.
One word of warning for people looking to buy an XRGB mini for their N64 - these machines are amazing for getting old 2D consoles to look good on large modern TVs but don't play well with the N64. Depending on the settings, they either look much too scanlined and 'artificial' or very blocky. It's best to try one out before purchasing it, although that's easier said than done..
So there we have it - I hope this is useful for obsessive types who are searching for the best there is. For everyone else, their current TV is perfectly fine.