There was a time when I asked questions such as this myself. I was NEVER satisfied with the answers I received. What is considered the "best" games is highly subjective. It's very difficult for anyone to recommend games to someone who may have vastly different tastes in games than you do.
I mean....some people actually like those Imagine games for instance, but most of us wouldn't even vomit on them let alone put them on our flashcarts or {gasp} buy them. Many people love RPG's, but I don't have time to play long drawn-out (and ultimately boring to me) games like that. FPS's seem to be all the rage for gamers these days, but I hate them myself. Pokemon......people go gaga for those games, but to me they are far too cutesy to even consider. I'm sure you get my point. I've read a lot of the "must have" lists around the net and out of the the dozens of games they would list, I would only be interested in maybe 5% of them.
I know it may be time-consuming, but you need to research for yourself what games you might like. Go to the "releases" section, look through the releases and when you run across a title that sounds like it may be interesting to you, look for reviews of that game. Don't go straight for the review score, read the review and see if it sounds interesting to YOU. That is the only way you can truly determine which games you'll like.
I know for a fact that if I listed games that I like and tried to recommend them to you, I would be flamed into non-existence by most of the community.