What do you all prefer and why? Which do you find more interesting?
First of all I can't ignore accessibility in my answer. My world is cold water and I can have it any time that schedule and conditions permit. That being said I have adapted to cold water, I know what to expect and can see the cool things like the changes of the seasons from dive to dive, month to month, season to season, year to year.
Warm water is likely to have much better visibility which is fun. I'm accustomed do diving in a smaller space with 10-20 foot visibility being common and in that space there is usually more than I can absorb so I don't fee cheated and enjoy wondering what lurks in the haze. Having no trouble whatsoever keeping track of a buddy or having long range vision in clear water is nice.
Warmer water is.....warmer. There's not too much to not like about less protection and lead.
Cold water has a more tactical feel with sort of a "mission accomplished feel at the end. Warm water is more carefree.
I prefer our north Atlantic plant life. Of what I have seen so far in warm water (Bonaire) Coral was neat and different but I found it to mostly be static and those great colors you see in photo's only really appear under lights once you do down do a reasonable depth. Our bottom is just more alive with color and motion with stuff swaying in the surge. The fact that most of our dives tend to be shallower than dropping off a reef of course gives us an advantage with the spectrum of light.
As for fish... In warm water you will see more fish more often and they will be more colorful by a country mile.
I need to pack and travel for warm water but then I'm on vacation away from it all.
I have found that anything that mixes it up will help keep the sport intersting and challenging. The Caribbean, springs of Florida, local fresh water, or the Quaries of Connecticut or Ohio, it's all good.
It's all good and your local diving will have you totally prepared to have a ball when you have the opportunity to travel.
Pete