Which is a better choice? New, or used preamp?

IMO, go for a used tube preamp from a well know manufacturing. That way you could save a lot money for some NOS tubes to tailor up your sound reference and maximize its performance. As far as reliable, I haven't got any bad luck with all the used tube that I bought on this website. Go luck on your quest.

I would focus on ARC used gear. First off if you purchase wisely, you will not lose any of your investment. The reason being that ARC is well established and their gear is extremely well made. So far as it sounding leaner than CJ, maybe their newer stuff but less so their vintage gear which IMHO is still desirable and offers excellent performance with careful tube selection and changing out some of the capacitors to enhance performance. Example, the classic SP-10 pre-amp that Elizabeth notes above. There are reasons its used value continues to increase and is still sought after by audiophiles and they aren't sentimental, believe me! The SP-11 and SP-15 changed the direction, more towards the leaner and accurate presentation but also superb performance, a matter of taste and system matching to be sure.

The fact that producing a new preamp today with quality construction will be more costlier for a manufacturer then that of yesteryear. Also some of them older preamps were built during a period of time when two channel was at its peak and alot of manfacturers were competing with each other for your dollars. This in turn produced some of the best sounding stereo preamps. I'm sure if you are willing to shell out enough money, you can buy a new quality sounding pre.

My recommendation is to buy used, and stick to an established brand. Eventually you WILL want to sell it, and resale value for an obscure brand is usually pretty dismal.

Good luck with the search.

I would recommend a used Emotive Audio Erato, Poeta or even Sira for the best sound and overall value in the price range. They don't come up for sale all that often but if you can wait a month or two you should be able to find one on Audiogon.

I also would respectfully disagree with the suggestion that the sound quality of older tube gear is equal to modern preamps. It is true that SOME vintage equipment and SOME vintage parts can offer unsurpassed sonic quality. I am thinking of Western Electric equipment and the like. These are exceptions though which is why they stand out.