I vote DMR & DSTAR over System Fusion. But let's look at the facts.
DMR - Radios are inexpensive. However, programming can be a ***** to a new user. Even if you get a decent code plug to work, chances are it is out of date, unless you get a fairly up-to-date plug. Repeaters are popping up everywhere. However, one radio will not get you on every system. The radios are either VHF or UHF, NOT BOTH! So, while cheaper than DSTAR or Yaesu System Fusion, you need two radios to operate both VHF and UHF DMR. Do you really want to carry two HTs just to access DMR? It can be a hassle, especially when traveling. Oh, while the majority of DMR repeaters can operate dual-mode (analog and digital), most of them don't. And yes, DMR radios operate both analog and digital… But only on UHF or VHF, no dual-band radios here!
DSTAR - Radios are more expensive but also dual-band. Meaning only one radio for both VHF and UHF. And, while DSTAR repeaters (by ICOM) only operate digital, you can operate both analog and digital with DSTAR Radios. Sure, the headache of registering for access on the DSTAR gateway can be a pain, you only have to do it once. (You also have to apply for a user ID on DMR to even transmit on the repeaters and talk-groups, so DMR is like DSTAR in this sense.)
Yaesu System Fusion - Radios are more expensive but also are dual-mode and dual-band. Repeaters are popping up but not lasting. The repeaters are built out of two mobile radios and fail if running at, what Yaesu said, true 100% duty cycle. Most failures are caused by the finals failing in the radios inside the repeaters. You can reduce the RF power and run a repeater amp but chances are, the repeater will eventually fail even at 5 watts. The club I belong to has had 3 YSF repeaters and all of them are back at Yaesu for repair for yet another time! Yaesu knows about the failure issues but does nothing to correct it, except tell you to run lower power out of the repeater. Pretty sad, yes?
So, you pay your money and take your pick. Honestly, you have to try them out for yourself and find which one you like the best.
I hope this helps… Some thoughts are my own about what I said above. Not trying to start a war among DMR/YSF/DSTAR users.