This is a good and original question! I had a chess partner like that, and I often without thinking why do we like playing each other for so many years. I think how overpowering or easy to beat is the winning ticket. I always felt he was slightly better then me, but I was always in the game (unless I blunder early in the game) And we reach wonderful end game play, where pushing the right pawn at the right time made all the difference. I must have given my partner enough challenge to keep his interest as well. Plus his wife made fresh cake, pies and coffee for us at each chess session
BTW, there are some great 1300-1400+ chess players here that I have played against and would never get bored playing them, they create interest in their games by playing good enough to where I have to do some serious thinking, and often they are making moves well above there rating!
The guy/gal that you always learn from after playing.Oh and in these scenarios lets just say there the same rating as you.
Is it someone who plays the same style as you with diffrent experiances
Someone whos style is the exact opposite of yours
Someone who plays good openings and knows the concepts very well
Someone who plays offbeat/unorthodox openings and knows a great deal of theory on these lines ?