A good kit build will have more care and attention lavished on it than a factory build could ever have. If it's a good kit like a Vans RV, coupled with a good builder you will probably never have a better aircraft. Once you have made your choice spend whatever it takes to get someone who is familiar with the type and has the knowledge and ability to give it a good pre buy inspection and report.
Components like engine, instruments and avionics should be by good reputable makers with support available. If it is the builder's second or subsequent build so much the better. Looking at the paperwork is very important. Who maintained it, what are the records like, does the paperwork match the aircraft and components, is it all legal. Again, it will pay to get someone competent to look at this side of things.
Do the ground work and you will get a great aircraft, for a price you could not build it for. Worked a treat for me!