If you are thinking Cowboy Action, then I wouldn't mess around and just get the Uberti 1873. I have a Henry Big Boy that i started out with. I works great, but you can't get it to go fast - no parts or gunsmithing advice I was able to find. I bought an 1873 and my times sure improved - it has the better springs and a short stroke kit and is a real bullet hose. I think if you talk to the cowboy guys, most would prefer the 73's after all that seems to be the most popular rifle since if you're really good, you can almost get all 10 cases in the air at the same time. If you aren't going to shoot competition, then you can't go wrong with any of them. But if you are planning to, I'm trying to save you from buying 2 rifles (not that that's a bad thing).
I vote Spencer! You'll just have to make your own ammo and get a centerfire block (unless its one of those modern copies).
After many years shooting other peoples lever guns, I decided to get my own for the upcoming deer season. (if rifle cartridges are legal)
I tried all types of lever guns and found the Marlin fit me well and was close to my budget ($400 used). I also like the lever gun without the safety, it makes it much easier for me to shoot, since I am left handed. I found a 1980 Marlin 30-30 in near mint condition at the 1500 for $325.
Well, this one looks awfully nice. 1873 Rifles
I saw an overview in the American Rifleman.
My first rifle purchase was a Win 94 in .30-30 (just cleaned it the other day and picked up another 200 rounds for it), my MOST RECENT (lever gun) was a Marlin 1895CB in .45-70...doesn't mean it will actually be my last...
edit...here I saw I responded to this thread back in November last...but the link is new!