what is a good tube pre amp out there...........

i have and love the conrad johnson tube sound. i have a pv10 and pv12, both sound fantastic. but how do i know if its the best if i have never tried any thing else. my associate equipment is: alon 4 speakers on the 12 and axiom m80's on the other, cj 2300a and 2500a power amps, rotel 975 and nad 545eee cd players, interconnect are tara labs vector 1 on both. audioquest speaker wire on the 10 and some home mades from axiom speaker co on the other. i heard about vtl, bat and others, please give me the pro's and con's of each you feel is best. also some fyi on proper amp/pre matching that im just learning about. thank s in advance.