Just like tubes, different transistors sound different. Tube equipment manufacturers are very quick to tell you what tubes are used in the products. However, transistor equipment manufactures typically don't tell you what is being used, the circuitry or topology.
So, as usual it comes down to what you like when you are listening.
I have hear some amazing tube amps and pre-amps. Likewise, I have also hear some amazing solid state amps and pre-amps. Don't let anyone fool you. both are great. I would take either.
It comes down to your style and listening preference.
But, as I have mentioned many times, make sure you are comparing apples to apples. First, establish a sound you really like. Second, establish a price range/point that offers products within that price range/point. Third, then go find tube and solid state equipment that you can listen to, hopefully in your home system or if not, in the store on the same equipment. Those really are the only two ways you can really tell the difference.
Also, don't let people when demonstrating equipment change other equipment at the same time. Remember, apples to apples.
Listen to a tube amp on some equipment, then change out that amp for a solid state amp (same requirements and price point), changing absolutely nothing else and listen again.
some dealers like car dealers have certain models that absolutely are trying hard to sell and will try to set them up so that they seem better than others. The only way to tell is apples to apples comparisons.
It is difficult, but there are tube fans out there that refuse to hear anything else, not matter how great or innovative the other product is. Same can be said for solid state fans.
I'm a fan of excellent engineering and great sound regardless of whether it is solid state or tube. Great sound is great sound. Every designer has compromises in the designs and sound of their equipment. Unless the product is a cost no object design.
A good dealer will help you with this if they carry great solid state and tube equipment. Audio shows are good also, but you can't really compare there. but fun non-the-less.
enjoy