The CLD-S104 is really a piece of junk, I won't give it anything. Its built cheaply. The only advantages I can see to it is it can be had very cheaply. I bought one at the thrift store simply because I've got a lot of laserdiscs (close to 400, between my girlfriend and I we have close to 450). I have it hooked up to my Sayett Mediashow projector and with the scaler box needed to upconvert the output to VGA it doesn't look too bad and displays a picture but I'd certainly not consider it for anything more than a backup player.
I don't mind my CLD-V2600 it has very fast start and stop times probably a result of it being a commercial player, and its picture quality isn't bad, it can usually be had pretty cheaply, seems fairly durable. While it will spin a disc up or down in no time flat it is pretty noisy as a result, I'm almost positive it has a more powerful motor than most standard grade stuff. Still the picture quality is decent, and I use its SVHS output. Granted the composite would probably give a better result but I've got it hooked up to my 32 inch LCD TV and have something hooked up to all available inputs except SVHS 2 so thats where it went. Still looks pretty good. I bought it when Media Play went out of business and liquidated the store fixtures, still had the remote too. Of my LD players it receives the bulk of the use.
I've got an RCA which is a rebranded CLD-M90 from Pioneer hooked up to my Samsung 27 inch HDTV. This is where my belief that the comb filter of the TV itself makes more difference than the player. I've yet to see LD look better, the picture on this will rival anything I've seen considering this is not a TOTL model the picture is so impressive you'd be shocked.
I have a CLD-S201 I believe it is hooked up to my Sony 42A10 42 inch LCD rear projection TV, here again this is a pretty low end player, a bit more solid than the S104. The Sony does a great job with it, will blow the picture up to 42 inches and it still looks decent given the resolution we're working with. Again, this isn't the primary player I use but it does the job should I choose to watch a movie in there.
My girlfriend has a CLD-990. I've heard this player had a firmware glitch that prevented play of a few discs but we've never encountered a problem with it. I like this player, it is very solid, and has next to no noise or vibration of any kind. The picture quality on her 27 inch LCD is good puts out a nice smooth picture thats plenty enjoyable.
Again, from my experience if you use the composite out and the TV has a good comb filter of its own the picture should look good regardless of the player.
My collection has extremely obscure stuff to the run of the mill. I've found some movies will have better sound mixes on the LD, particularly if the movie was rechanneled to 5.1 for the DVD release when it was originally a stereo soundtrack. Some well done LDs looks way better than the DVD, particularly if the DVD wasn't particularly good. May be slightly less sharp on the LD but you've got to factor in that some of the DVDs have terrible artifacts.
Honestly there is hardly anything invested in my collection from a monetary standpoint, I'd guess less than $500 for all the players and discs, but I won't part with them. If I see any LDs floating around cheaply or cheap players I always pick them up.