Marine Aquarium TIME 2 has the same Fish as MA2, with the added clock/calendar/logo feature.
Best? Matter of opinion really, but if you can't decide you can buy both!
Seriously, we recommend downloading the programs and running them in demo mode to see for yourself. This procedure is outlined on the SereneScreen.com site under the FAQs here:
http://www.serenescreen.com/support/faq.php