My favourite year in video games is probably 1998. We had the beginnings of some really great game series, like the english Pokemon Red & Blue, Half-Life, Spyro, and some of my personal all-time favourites like Banjo-Kazooie and Metal Gear Solid. There were plenty of good sequels too, I remember spending a lot of my time playing stuff like F-Zero X and Gex: EtG. I should probably throw Ocarina of Time in here somewhere too.
More recently, I'd have to say 2010 takes my second place. There were some really great games that year, and a lot of them ended up becoming some of my favourites, like MGS: Peace Walker, Halo Reach, Fallout: New Vegas and Super Mario Galaxy 2. There were plenty of others I really enjoyed that are classics now, games such as Mass Effect 2, CoD: Black Ops, Heavy Rain, Red Dead Redemption, DKC Returns, and Bayonetta (although that was released in Japan 2009).
There's plenty of games I didn't list, but those are the ones that really stood out to me. I sunk so many hours as a kid into my N64, and '98 produced not all, but a lot of my favourite games of the era. 2010 may have had some incredible games too, but it can't compare to the impact 1998 had on my life.