Any tube amp worth its salt will sound better after 5 minutes than a solid state amp that's been on for 5 weeks.
Double lol...
Anyone that makes blanket statements like this hasn't heard a lot of gear and they certainly haven't heard the best that both sides have to offer.
It's very much a matter of personal preference when choosing between the two. Often times there isn't a "Best" per se, especially as you get to the top of the line with all of the major mfrs.
It's a lot like speakers. Believe it or not, there are a ton of people out there that hate panels! I don't get it, because it's by far my favorite sound, but everyone has their preferences.
I have found that people shake out into a number of categories. Some only care about that magical, bloomy midrange. Otherw just want powerful bass, some like detail, others like imaging, while still others want dynamics above all else.
I haven't heard everything, but between TONE, working for The Absolute Sound and horse trading my own gear around for the last 30 years, i've probably owned, reviewed or listened to most of it in good rooms properly set up and there are a lot of different ways to audio nirvana.
I was a dyed in the wool tube guy till I heard the Premier 350. But that doesn't mean I didn't enjoy the LP140's, the Manley 250's and the ARC Ref stuff tremendously. I've heard the Summits now with about ten different big amplifiers (I still hate em with MC275's, sorry) and its a subtly different presentation with all of them.
I like my flavor the best, but all the ones I heard were very good and I could have easily lived with any of them.
What's really important is finding the flavor YOU love.
What excites me about the Summits with the combination I've put together is that I've had quite a few people walk in my studio door saying "I hate panels, I don't even want to listen to those...." Walk out being blown away.
It's all about the setup! And keeping an open mind!