It really depends on which remakes you're talking about. Firered and Leafgreen were nice, and I have a soft spot for them because Leafgreen was my first Pokemon game and I have a lot of memories with it, and I liked the Sevii Islands and all the secrets contained within them. But in terms of content R/B/Y amusingly have them beat, and not even intentionally. Because of just how wonderfully perfectly horribly broken the original games are, the amount of things you can do within them is really only limited by your imagination and programming knowledge. Wanna make your own scripts? You can do that. Befriend horrifically glitchy Pokemon and explore eldritch lands, you say? Sure, why not? Toy with abilities and powers you can't possibly hope to understand and observe the hilarious results? Have fun. Heck, if you have a special item (8F or wsm, depending on the version), a team of special Pokemon with special movesets and certain items to accompany your debugging device you can make your very own minigames, like Pong or Snake. Awesome.
As for G/S/C and HG/SS, they're really more or less equal. G/S in particular are awesome games by themselves but also have similar bugs and glitches, and if you know what you're doing you can do just about anything, though not as much as R/B/Y. And HG/SS.... dear GOD I can't praise these games enough. These two games took what was already a wonderful experience and made it even better, adding in a feature we haven't seen since Yellow and adding in new areas (and fixing Kanto) while keeping the region as we remember it. I love these games to death, and they're very wonderful games that really set the bar in what a remake is supposed to be.
As for ORAS and R/S/E... eh.... I like Emerald, I like the Pomeg glitch that again allows you to break the game in hilarious ways, I like how Team Aqua and Team Magma were fighting each other and you had to summon a giant wyrm to prevent the region from going into chaos. I've never played ORAS and I don't really plan to, but I never liked how they redesigned the protagonists and antagonists and kept the alternate storylines in Ruby and Sapphire without adding anything in from Emerald, which was really the more superior version of the game, and I dislike the whole Mega Evolution push. The games themselves seem to have a lot of flaws, and don't really have much in the way of new content to compensate for that (like the Battle Frontier, which really should have been included.)