Well, I am not really bashing on the k3 pro. I've shared my opinion before - for me its biggest downfall is its tonal accuracy. It is a bit too cool and the timbre and note thickness are off. Also, the male vocals are kinda pushed back for my liking. That accompanied by the somewhat loose and slow bass seals its faith.
I don't really have one as there are many iems with strong points that I like. To list few:
I really like the brainwavz R3 for its specific sound, very well extended and detailed but buttery smooth; Due to its smoother character it is a touch lacking in clarity and crispness, but overall it's a great buy if one wants a neutral and detailed sound without harshness (and can get accustomed to the slightly weird form factor).
I also really like the Dunu Titan 1/Fiio Ex1. It can be a bit peaky but the sony mh1 hybrids smooth it at the right places and the clarity and tone are extremely good. The lows are on point with good speed and control. The close to non-existent isolation is a big con though.
The brainwavz B2 is also great. I included it because it should be re-released any day now with better build and detachable cables for under 100 bucks and if they managed to retain the sq, it will be a winner. Great speed, great clarity, great crispness. It can be a touch splashy in the treble but this can be alleviated with the right tips. A con is that some people might want more weight and presence in the lows, but it has a slightly distortion and is not an iem for someone who thinks he can eq the bass and it will be fine.
The vsonic gr07 is another staple. Great performer overall, although as many know it has a bit peaky highs prone to pointing out sibilance. The bass region is great though. Attack and decay are spot. For me the gr07 would be a top pick if they managed to push the mids a bit forward and sweeten the treble.
There are many other great iems, I would rather go for like vsonic vsd3s, the ety hf5, the now long discontinued mee a161p, etc.
Overall, I hate slow and uncontrolled bass, I need a solid and tight hit on the impact. I like neutral and clear mids with good vocal presence, so pushed back vocals are not my preference. And I like well extended highs with good clarity and some sweetness to them. Ultimately, the treble is the harder thing to get right and most entry and mid-fi gear rarely get close to what I want, which is a certain sweetness and liquid smoothness while still being very clear and present.