When I bought my 1982 Pöllmann, it was mainly a question of availability. As a student without car, and in a country with a lot of distance between each bass for sale, I couldn't be too picky. In fact, in order to get a loan for "extra studying material" you had to take the loan during the first half of your studies - within 1,5 or two years. So I borrowed this one from my teacher, and I didn't even really like it - looking back, I didn't even know anything about basses back then! - but at least I realised that it was probably the most bass I could get for my bucks.
I love it more and more. It's sounding better and better, and that's not just my playing. I can take it to any gig and it will do, it's failry sturdy as opposed to some frail old basses which feel like they might fall into pieces (this one hasn't even had a crack!) and it sounds good from top to bottom. I hope I'll be able to keep it throughout my life, but it's not my 'ultimate' bass. The body is larger than the scale might imply, and so the shoulders are a bit too high, and I also feel that it could be easier to reach properly into the E string. Which is where I almost wish I had played French bow...
So, what I'd want in my next bass is basically improved playability. The shoulders are less much of a problem. Of course, I'd be looking into an older bass, for the sound, and hopefully that feeling that somebody has already been playing this bass properly for ages. Actually, there is this bass that I can't get out of my head... the Swedish one over at the Contrabass Shoppe. What's probably the best sounding Swedish built bass (possibly along with a Johan Öberg of the 1700s) just shouldn't have left the country. My teacher went over there to try out some basses, and he also remarked that I should have that bass. Unfortunately, we are talking £50k, and that means debt until retirement, even if I could get a loan...