well ill put my 2 cents in
for the first question. ill play a solidstate anyday, tubes are warm, but they also have something about them that i think plays with your sound too much. my fav. ss' are definitly peavey's, they just have that "feel and touch" to them. i have my little bandit 112, and my marshall g100hcd, and even though the marshall sounds good, i prefer teh peavey. im actually gonna go buy a peavey dirty dog distortion pedal so i get some of that feel transfered.
for the second question..... im not a big knowledge on tubes, but i hear the EL34 is the best.. dont take my opinion for it though, i dont know if ive even ever played on one, all i know is the best sounding tube amp ive ever used is the peavey jsx.. it plays beautifully