I use the stock HTC one with the mod to enable voice to text - I don't actually use this feature, but I like the other modifications it allows. For example, the ability to remove the horribly annoying pop-up showing which key you pressed and the ability to re-instate auto spaces after punctuation - the stock keyboard on my HTC hero did this until a firmware upgrade apparently disabled it.
For portrait mode I use the numeric pad layout because I find it a joy to use for tapping out quick messages.
Ps. Have any former Hero owners noticed that the sound and vibration feedback on the Desire isn't nearly as accurate and helpful as it was on the hero? Not that it matters since the Desire doesn't have an issue with keyboard lag, so I've found I don't need any feedback enabled.