Well, i think it's better explain what each do and how it works before answering you:
Bootmii@Boot2: When wii boot, he pass through 3 type of boots that we call boot0, boot1 and boot2 and then the System men ios and the menu itself. What BootMii@Boot2 does is use a bug in the boot1 to be able to install the files in boot2 and then protect your wii (Not sure about that part) but nintendo fixed the bug in the wii's middle 2008 and ahead so its not possible to install on newer wii's, and that is your case.
Bootmii@ios: As the name says, when the boot1 bug got fixed the team Twizzers had to find a way to install bootmii so was decided to install as a normal ios in the last slot, the problem comes because he doesn't start before wii menu so in a case of corrupted system files it will be not so useful to recover as boot2 install.
Priiloader: He works in a totally different way than all bootmii's, patching system menu IOS to add some hacks like block update and other functions, he really not good as bootmii's but with him you can forward directly to a loader or homebrew channel on start or recover your wii from a semi-brick or theme brick and it works with every
Wii version (in theory)
Now what you want:
It's better to you install both Priiloader and BootMii@ios to at least protect from some bricks and some other nice features
Also, sorry for any mistake