This is where it gets a bit iffy. The source is identical on all the MGM discs, just with better image with each successive issue. The SE DVDs will give you superior image but at a cost: Edge enhancement, compression artifacts, cropping of the first three to 1.78:1, spots of interlacing, and greatly enhanced video noise that isn't film grain.
I lucked out and got a great CRT set, so I stick with LD. (Though I only have a few of the SE titles to be honest. Why some people charge an arm and a leg for those old boxes is beyond me.)
On the first three I still stick with the Connery Collection as it looks exactly like the VHS tapes I grew up on. I haven't found Criterion copies yet, but the MGM discs show off the color I'm used to. The PCM mono is another big draw and sounds great, though FRWL has quite a bit of print source background crackle like listening to an LP. (It does however have a great isolated score and effects track that is dedicated and not faked like some others I have. Chinatown's still has the dialogue audible.) Also, these are theatrical 1.66 as opposed to the Criterions which are cropped.
I don't know if you could call it an International version; it's really just an alternate mix, and the more I dig into the films troubled history, it may actually be the original mono audio. Every mono track utilizes this mix, and those that are different seem to all derive from the 1995 Dolby Stereo surround mix done for the CAV boxset. To get this mono audio with notable differences either the 1989 disc or CC Vol. 2 will work. They seem actually to be identical, save for two odd audio glitches on each. (My 1989 copy has Connery stutter in Cafe Martinque and order Dom Perignon Perignon '55. The CC version has the music essentially vanish for a minute or so whilst entering his hotel room and rewinding the tape. I don't know if these are just my copies or errors. Both very small.)
The CAV collector's sets of GF and TB are the best looking and pressed on LD in beautiful boxes, but more expensive with TB having the new remix and GF being the first release to have those frames snipped out of Oddjob's car turning off the side road with Mr. Solo. TB is necessary for the new mix (sounds phenomenal) and the employment of full CAV for image fidelity. These were later issued in CLV THX editions which are very scarce.
It was thought that TB went through restoration for this CAV set and has better color, but after very close comparison between all three discs, it just isn't so. All three utilize the exact same transfer with the exact same damage marks, tics, and one really stubborn hair in the gate. The CAV looks slightly better due to being newer and in the CAV format. (You also get this on Side 3 of the other two.)
If you want all the 60's era, both Connery Collections+ OHMSS should do as I haven't seen any real difference between the 1989 series titles I own and those found in the sets. I have TB and YOLT in both but typically watch my 1989 discs as they are cleaner and my copy of the CC vol. 2 is pretty worn. You'll get DAF too if you go this route but the print used for DAF on the LDs is pretty worn and damaged in places. At least it has the correct timing.
Pick from these and get whatever is cheapest and in the best shape. Condition really matters on these and you don't want video noise popping up throughout. (Poor DAF.) You will certainly want OHMSS on LD though, as it is the only release (Besides my 1995 Letterbox VHS) that is fully uncut and without error in picture or sound.
To be honest, I haven't needed anything else for the 60's era since going the LD route. The SE DVDs aren't that great looking and their flaws are really apparent on modern displays. Doctor No has horrible video noise that coats the whole movie in speckling. OHMSS is quite good but has errors and missing dialogue.
The first time I popped in anything from this era was the 1989 YOLT disc. Things looked good on the opening, but as soon as it cut from the official's meeting to Ling's apartment -BAM! Skin tones, the red walls..everything was properly back. TB was the same, and things like the bomb sled really jump out colorwise on a CRT. Skin tones are perfect. OHMSS has similar vibrant spots of color.
I think I have to watch these again now after talking all this time...;)