A memorable song doesn't have to be complicated, but it also doesn't need to be boring.
On a positive note, if you want to play a lot of songs, learn the chords G, Em, C, and D. If you want to add even more color to the sound, there is a different kind of G and C chord, and the C chord has a different name. It's called Cadd9.
I lament that so many new songs are the same chord patterns, or they'll take a short 4 or 8-measure pattern and loop it through the entire song. This is frustrating because these songs don't seem creative, memorable or long lasting.
In the '60's and '70's for instance, it seemed like many artists were, perhaps, given more freedom to experiment. Within the same song, they used different tempos and sections. It wasn't all the same beat throughout the entire song. They used different recording techniques.
I have heard stories of rock bands putting amplifiers in an empty concrete swimming pool and then mic-ing it, etc. Different sounds that were real creative.
So many new pop songs are just so bland. It seems to be more of a dance beat than anything else.
An example of some good songs with the G, Em, C and D chord pattern are by Taylor Swift. In my opinion, she has written some great songs by using those 4 chords and a capo. Her songs are not boring.
Another famous example is Jason Mraz' I'm Yours, which uses essentially the same chord pattern throughout the whole song but provides a catchy lasting rhythm.
Also, a lot of amazing worship songs use these same chord patterns.
