I hold some B in my IRA. Less volatile, no potential for higher share price but good yield.
If you are looking to pick up preferreds, be patient on price and you can pick them up a little closer to par...they are pretty high right now. Of course, use a limit order as noted by jerseyvinny they are thinly traded.
For starters, be aware the trading volume for B and C is very low. Some days it is zero. D is the only one trading in volume. They sell above par and are callable at any time so yield to first call can be negative. Their financial situation is good so I don't think they will suspend interest again. Would feel better if they sold at par or at a discount but in this yield-starved market, that probably ain't gonna happen.