Great question!
I use the personaliTea (about 24 ounces) to make black tea that I share with my family (it is the only tea I can get anyone else to drink around here). I brew it "western" style, one teaspoon of leaf per 6 ounce cup (plus one teaspoon "for the pot") and then we share the pot of tea...sharing a pot of tea with my family is a source of pure joy for me. The infuser with this pot is large enough that the leaf seems to expand very nicely. However, if you are using the infuser you do have to make a pretty full pot to have the water reach the basket (does that make sense?)
I use the smaller pots for the teas that are better (by my taste) brewed in small amounts....which works okay for me since I have to drink them alone

If I manage to get someone to join me, we'll each just use smaller cups.
If you get anything unglazed, you probably want to stick with only one kind of tea in that pot (e.g. I only use my red tokoname for Japanese greens) since there is a transfer of flavor to the pot over time (strong flavors might stick around to flavor or scent your other teas).
And if you're going to do Japanese greens you need a pot with a fine screen or fine ceramic screen (can't remember the word for this) since Japanese greens can have pretty small bits and need room to expand (i.e. they don't work well in an infuser basket...you'll cheat yourself out of some flavor if you use a basket).
I am by no means an expert, but since loose leaf teas are fairly new to me, I can sympathize with the dizzying array of teaware that is available and I can pass on the info about what has worked for me. There is every temptation to jump into spending lots of $$$ on pots, but I've found that quality loose leaf tea brewed at good time and temp, tastes awesome no matter what you brew it in.
Having said all that, I think I must buy the glass vessel that Sal posted a picture of last week...I am sure that there is some scientific reason why I need that particular brewing vessel!!!
Have fun,
Dreamer