Welcome aboard and enjoy the hunt for that perfect-for-you boat. If you want to dive (or fish like I do) you'll probably want a cockpit for good water access. If you want diesels, you'll find more choices in 32 ft and up. Not that there aren't 28-30 fters with diesels and a cockpit (like Heron's beautiful Cape Dory) but the choices become fewer with a 30 ft length limit.
I find my 34 fits me "just right" as a boat I can single hand with ease, can drink 6, feed 4 and sleep 2 in comfort....or sleep 4 with a certain level of "friendliness". A dry head with separate shower and systems access is also key to me but may vary for others. Also, to be able to afford this lifestyle, I needed to be able to perform all routine maintenance myself.
If I was to do it all over again tomorrow, I'd probably buy the same boat...unless I had lots more $$.