Already created a thread like this several years back...
http://www.clubtokyo.org/discuss/viewtopic.php?t=14677
Here was my response...
Godzilla 1954: My parents insisted I saw this film long before I saw any of the others and that I didn't respond to it at all. I don't remember that. When I did finally see this movie for a second time it was after I had already seen several other Godzilla films - probably sometime in 1987. I saw this one via the old Vestron Video that we rented from a local Rite Aid (before Blockbuster became a monopoly). However I really didn't appreciate the movie at all until I was much older and finally saw the Japanese version.
Godzilla Raids Again: Weird story with this one. Back in the 80s my local syndicated station (WPIX, later WB) would show monster movies every Saturday on the "Morgus Presents" show. Morgus was a creepy mad scientist who would host lots of old monster films, many of which were kaiju movies. Godzilla Raids Again was one of the later Godzilla movies that I had yet to see. However, a scheduled airing of the film was replaced by an airing of Rodan and I remember having to wait several more weeks before they actually did air it. I don't recall liking this one much either, and it bothered me to see Angilas so brutally killed by Godzilla. Toho had reissued the movie by the time this aired so I didn't see this one with it's original "Gigantis the Fire Monster" title until I got ahold of the Video Treasures tape a little while later.
King Kong vs Godzilla: I caught this one on another syndicated station (WWOR, which would later become UPN) on Thanksgiving weekend along with King Kong Escapes. I remember being really sick that weekend, and this film brightened my day.
Godzilla vs the Thing: Don't remember much about this one other than my grandmother having taped it one weekend and - in an effort to find a copy of the film on VHS at the local video store - I accidentally picked up the original 1961 Mothra thinking it was the same film. At that point I thought all Japanese monster movies had Godzilla in them. Rude awakening, that. Like the original Godzilla, I didn't really like this one til I was old enough to appreciate it.
Ghidrah, the Three Headed Monster: I don't remember this one ever airing on TV in the mid-to-late 1980s. I saw this one thanks to a public domain VHS tape. I loved it at the time, and I still have a soft spot for the American version no matter no inferior it is to the Japanese original. Next to Destroy all Monsters and Godzilla vs the Smog Monster this was one of my favorite Godzilla movies growing up.
Monster Zero: This was the second Godzilla I ever remember seeing. I caught this one about a half hour in one Saturday on (you guessed it) another local station. I don't remember much of it - and I didn't see it again until I got the Paramount video years later - but I do remember tuning in just as the Xian saucers were retrieving Godzilla and Rodan. Having never seen Rodan before I wondered why they were pulling a big rock out of the mountain side. This was my first exposure to King Ghidora, and I LOVED him.
Godzilla vs the Sea Monster and Son of Godzilla: These two I saw at the same time thanks to a friend of my father who was nice enough to tape them off of cable (TBS I believe) since my family wouldn't have cable until I was in high school. I don't remember liking Sea Monster much at the time but I adored Son of Godzilla. In fact, I remember being very upset at the ending the first time I saw it. Today the ending still brings out a little internal emotional response in me.
Destroy all Monsters: Probably the fourth or fifth Godzilla movie I ever saw. This aired on the local WNYW station a few years before it became the FOX network. On weekends they'd show "The Drive-In Movie", which had a neat little neon logo and a very catchy saxaphone tune. I saw several Godzilla movies this way, but Destroy all Monsters is the only one I still actually have on tape after all these years, sandwiched between the ALF pilot and an episode of Small Wonder. I really, really hope the tape never wears out, but I know some day it will. Upon seeing it for the first time it instantly became by favorite Godzilla movie - despite not knowing who half the monsters even were. It's still my favorite to this day.
Godzilla's Revenge: This one was one of the last Showa Godzilla movies I saw, sometime late in 1988 or early 1989. This one aired on the Morgus show and since the film itself was so short the Morgus host segments were longer than normal. It was unbearable since I just wanted to see more Godzilla. I loved it at the time and I still get a big kick out of it.
Godzilla vs the Smog Monster: I think this one may have been the third Godzilla movie I ever saw. Like Destroy all Monsters I saw it on the Drive-In Movie on WNYW. I was obsessed with it for a long time and today I'm still fascinated by every aspect of it. It's trippy as all hell, off beat, insane, odd, bizarre and just plain weird and I loved every damn second of it. I still do. And when I was a kid I wanted that giant Bullmark Godzilla sooooo badly.
Godzilla vs Gigan: This is the Godzilla movie I thought I'd never see. By the middle of 1989 I had seen every Godzilla movie. But at the time this one was considered a lost film. That is, until New World Video put out the international version in 1989. Maybe it was the mere fact that it took me so long to see it but I loved it despite all it's flaws. It's still high on my list of favorites.
Godzilla vs Megalon: I got this one via the Goodtimes VHS from The Wiz (remember them?) Sadly the tape crapped out before the big battle, which annoyed the living hell out of me because I had never seen Gigan before and I was dying to. Thanks to that atrocious Jim Harmon book (which didn't caption any of it's photos) for a long time I thought Zone Fighter, Spilar and Wargilar were Jet Jaguar, Megalon and Gigan. Hey, back then good info was hard to come by.
Godzilla vs the Cosmic Monster: Another one I saw via the "Drive-In Movie" but in this case I saw it a little later than most of the others. I loved it for a variety of reasons. I was fascinated by the graphic Mechagodzilla vs Angilas fight (even though I didn't like seeing Angilas get hurt), the music was enjoyable and I couldn't get enough of that King Seasar song.
Terror of Mechagodzilla: Aside from G'54 (which I don't remember) this was the first Godzilla I ever saw back in 1986. On a whim my grandmother taped it for me one Saturday afternoon and I remember walking into her house just as Godzilla popped up for the final battle. I was instantly hooked for life. This airing also had the original prologue attached to it and believe it or not I still have a copy of the original tape this was on. Like the tape with Destroy all Monsters I know one day the tape will stop working and I'll have to throw it out. I keep an original Japanese poster for the film right above my computer monitor because of how significant the movie is to me.