Which is a better speakers choice?

The amp you pair with the speakers can go a long way towards transforming the performance of the speakers. Choosing wisely makes a big difference.

What type of music do you listen to? Do you play loud?

I like the sound of proac better, but they are both good sounding - just a matter of your subjective preference.

You don't like the present sound now? It should be pretty good already...

The Rega got good write up in hif magazines :

http://www.whathifi.com/review/rega-brio-r

... and proacs are good speakers as you know.

What source are you using? Perhaps the weak link is there, no? You can't fix bad beginning somewhere down the chain.

I listen mostly to jazz like krall, norah jones, etc. then sometimes i listen to coldplay, the verve, jack johnson, ano so on. No i never listen loud on my system, i usually set the volume dial to 8-9. On sources i got some good ones i have a marantz sa14 for cd playback and a rega p3-24 w/ ortofon 2m red for vinyl playback. All wired with DH Labs. My system is good at first but when i listen more it made me realize there something missing.. Is it from the cables maybe? My system doesnt have the weight and body..

Xtian,

My system doesnt have the weight and body..

The last post immediately stuck to me that you are missing the correct "gain" in your system. Then I checked the spec on the ProAc and find that they slightly less efficient speakers. I have had similar experience when I moved to a larger volume room. After I got the correct gain, my speakers now sound awesome.
The Rega is 50Watts, while the Leben is 15W. I think, for the ProAcs to sound better, you might need more power. So going to Leben may not help. The Harbeth is less efficient. Now understand that I am basing this all on the numbers I am seeing on the component sites.
Do you have anybody close by that you can reach out to, who has a more powerful amp? You might want to try that amp in your system and see if you get back what you are missing. That might be your solution.