Having bought and played many RPG as well as those listed in my top five most important ones I thought I would discuss some of the other ones I enjoyed too. Originally I was going to call this post "Other RPG I have loved", but decided that not all of these are truly ones that I've loved, even if I would still call them.
As well as Traveller I played Metamorphosis Alpha heavily, which in its first edition days had a ruleset similar to early D&D, but I always liked the setting trope for MA with the lost starship. This has had a number of new editions which I haven't bought and I have to admit the more detailed setting for the latest edition is actually something I'm not so keen on as I prefer to make my own details of the setting and have tried different reasons why the starship Warden lost its way and the organisation aboard collapsed.
Toon is a game that I still like for its emphasis on fun and that the rules are there as guidelines rather than to be obeyed in all circumstances. I didn't play it that much as I got Paranoia not that long after and I preferred the darker humour with the game.
Bushido was a game that I played a lot less than I wanted to, largely as by this point we had already been playing D&D, Runequest and Traveller for years and yet another game system did not appeal to the players despite the appeal of Japan as a setting. The mythic Japan is far closer to the historical model than the setting of Rokugan used for D&D's Oriental Adventures. It is a hell of a long time since I looked at it though I still have my copy tucked away in my collection.
Bunnies and Burrows was one of the first RPG I actually bought in the original FGU edition. I always had a certain amount of difficulty getting players compared to D&D as to teenage boys (as my group was at the time), but this did have a lot of ideas that were new for a published RPG: martial arts, a skill system and most unusually for a RPG at that point no human characters. In fact pretty much all the characters would be rabbits, thought the stats would allow other species IIRC.