Oy, that's tough. If you KNOW what you want, the used market is great. I would go out to shops and listen to speakers. You might find something you like new, or you will be able to narrow down what you like.
Nothing's as lifelike in the midrange as a single-driver speaker. But, these won't sparkle in the treble like a good 2-way monitor. Bass is likely to be punchier in the monitor, but midbass (think standup, acoustic bass) will be better with a single-driver. SD's sound more like music to me, with 2-ways more like hi-fi, but it's all a matter of personal taste.
Good luck!