In general tubes tend to be warmer than solid state. In high end products they are not warm but just more realistic.
In your situation. First, if you want to make sure your new purchase delights you, and does not just trade off one set of weaknesses for another, then I always make sure the increase in investment is at least 2x my last.
Assuming you want a better sounding system over time and given the price range you are considering and how important the preamp is, I would recommend considering putting $1200 in and buy a used tube preamp from a well established high end company… Rogue, Audio Research, or Conrad Johnson. You will have to get a moderately old one… but they tend to last forever and the sound is extremely musical.