I had the same issue recently that you're facing. I'm a USA player and the sad fact is that at the 6:00 pm Pacific Hours and forward, getting groups or doing any pvp in Battlegrounds isn't going to happen. And it's not the server's fault - if we got into a time machine and went back to the launch of EU retail Blizzard servers, this one would be superb in terms of faction. 1200-1300 on week nights and up to 1500-1600 during week ends during EU hours is extremely reasonable in terms of retail server load. It's right across the line of a "high" population server for that time.
So, why am I still here and not on Nostalrius? There's a few reasons at play. I'll list them.
1) The server staff has never lied to the player base once. The ONLY time there has been a discrepancy has been with the cross faction mounts, and that was an honest mistake with no easy solution at hand for it. About every other private server in existance can't say the same thing involving the topic of Dev and GM honesty.
2) English speaking communication lines between the staff and players regarding server issues and discovered bugs. I was involved with the open beta timespan and was flat-out blown away with how my reporting discovered bugs with proof from the 2005-2007 era was recognized, acknowledged, and put on the list for being fixed. It was all done with a matter of transparancy, and regardless of my spoken language or nation of origin, it made no difference to the server staff. My input had the same value as anyone else's. This is what killed Valkyrie server. This is hugely important.
3) Care shown from the server staff in terms of enforcing rules and rolling out server updates for bug fixes and stability issues. I don't have to really describe why this area is so important, and I really doubt I have to describe what evidence we've witnessed in how Chero and the team have been handling the server. They have been incredibly professional, beyond a standard Blizzard Entertainment held in the past or probably is currently maintaining.
4) The Open Beta. I mentioned this before, but I didn't go over why it was so FUGGING important. Nostalrius launched with a myriad of stock mangos core bugs and exploits that were taken advantage of by players who knew about them and planned ahead. This is why there were so, so many max level characters within a very short span of server life time, WITH epic mounts, and a very vast number equipeed with BIS pre raid epics like Ironfoes and Sunrazors. This was because their server staff rushed the launch to 'win the race'. Kronos didn't take that route, and held a Beta, stuff was found, and NONE of those issues are present on this server. No one was able to exploit for free levels, gold, or gear.
5) Scripts. Even today, go ahead and roll a new tauren on Nostalrius, run it to the starting area level 3-4 quillboar caves, and aggro a caster quillboar that will cast lightning bolts at you. Now, move your character out of line of sight and tell me what happens. I can tell you what happens on Kronos. The caster will stop casting and move forward to find you in Line of Sight again so it can start casting once more, or melee your character if it's in that range. On Nostalrius this is still broken. Ranged AI mobs merely stand in place if you move out of LoS and do nothing. I could cover this page with script and bug differences between the server, but that's a bold example I felt the need to actually cover.
6) I decided to stay here to be a part of the solution if I can. All this server needs is more NA players, and the way to do that is to make some videos highlighting the quality of Kronos Scripts, character abilities, and instances. So I'm doing that and I'm going to host them on other gaming websites (Not Blizzard, and not rival 1.12.1 server forums) to direct attention. It's within our power to get more people here, so I figure - what the hell? I think it can be done.
