Well, I chose the WZ/Azel model...can't beat those two.
As for whether Riker should have been given his own command, I say no...because to my mind, he himself didn't feel he was right for command. Every single time he was offered a command he turned it down...that tells me he wouldn't be fit for command. True, he proved himself a capable diplomat, a great tactician and had a good rappaort with the crew, all essential in a Starfleet Captain, but....he was uncomfortable with the move. Rather than giving him a ship, I would have put him in a staff job for the rest of his career.
As to why the ships keep getting bigger...human nature. We want the other guy to look at the ship and say, "HOLY CRAP!!!"
And, the number of ship styles can be explained as, they were all designed for specific types of missions. But, it is true that there are way too many classes out there. I mean, look at SW...they've been flying some of those ships for hundreds of years and still kickin azz
In some cases it would be too costly to upgrade the existing ships, but the vast majority could be brought up to speed quicker and cheaper than designing a whole new ship.
B&B just wanted to try and get rid of more of Genes influence...the E-D was the last Enterprise to be approved by Gene, and B&B want to turn ST into their baby. What they're really doing though is killing it.
Anyway, the WZ/Azel Titan is my vote, and no to Riker getting a command of his own. I mean, who want a Captain with performance anxiety?