I like to use column view with my org agenda. One of the custom
properties that I like to view is the priority. Here's what I do to make
that happen:

    (setq org-agenda-overriding-columns-format "%TODO %4PRIORITY(Pri.)
    %50ITEM(Task)")

Using Org 8.2 I was able to view the priority in the column
view. However, since I've upgraded to the latest stable version of Org
I now see "B" when the priority is empty.

Emacs  : GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
of 2017-09-12 on hullmann, modified by Debian
Package: Org mode version 9.1.13 (9.1.13-elpa @ /home/tom/.emacs.d/elpa/org-9.1.13/)

current state:
==============
(setq
org-tab-first-hook '(org-babel-hide-result-toggle-maybe org-babel-header-arg-expand)
org-speed-command-hook '(org-speed-command-activate org-babel-speed-command-activate)
org-occur-hook '(org-first-headline-recenter)
org-metaup-hook '(org-babel-load-in-session-maybe)
org-confirm-shell-link-function 'yes-or-no-p
org-agenda-custom-commands '(("." "Simple agenda view" ((tags "+today" ((org-agenda-span (quote day)))) (agenda ""))))
org-after-todo-state-change-hook '(org-clock-out-if-current)
org-from-is-user-regexp "\\<tom-o\\>"
org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer)
org-agenda-before-write-hook '(org-agenda-add-entry-text)
org-babel-pre-tangle-hook '(save-buffer)
org-mode-hook '(#[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-show-block-all append local] 5 "\n\n(fn)"]
#[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-babel-show-result-all append local] 5 "\n\n(fn)"]
org-babel-result-hide-spec org-babel-hide-all-hashes)
org-bibtex-headline-format-function #[257 "\300\236A\207" [:title] 3 "\n\n(fn ENTRY)"]
org-archive-hook '(org-attach-archive-delete-maybe)
org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org-cycle-show-empty-lines org-optimize-window-after-visibility-change)
org-agenda-view-columns-initially t
org-agenda-span 1
org-confirm-elisp-link-function 'yes-or-no-p
org-metadown-hook '(org-babel-pop-to-session-maybe)
org-link-parameters '(("id" :follow org-id-open) ("rmail" :follow org-rmail-open :store org-rmail-store-link)
       ("mhe" :follow org-mhe-open :store org-mhe-store-link) ("irc" :follow org-irc-visit :store org-irc-store-link)
       ("info" :follow org-info-open :export org-info-export :store org-info-store-link)
       ("gnus" :follow org-gnus-open :store org-gnus-store-link)
       ("docview" :follow org-docview-open :export org-docview-export :store org-docview-store-link)
       ("bibtex" :follow org-bibtex-open :store org-bibtex-store-link)
       ("bbdb" :follow org-bbdb-open :export org-bbdb-export :complete org-bbdb-complete-link :store org-bbdb-store-link)
       ("w3m" :store org-w3m-store-link) ("file+sys") ("file+emacs") ("doi" :follow org--open-doi-link)
       ("elisp" :follow org--open-elisp-link) ("file" :complete org-file-complete-link)
       ("ftp" :follow (lambda (path) (browse-url (concat "ftp:" path)))) ("help" :follow org--open-help-link)
       ("http" :follow (lambda (path) (browse-url (concat "http:" path))))
       ("https" :follow (lambda (path) (browse-url (concat "https:" path))))
       ("mailto" :follow (lambda (path) (browse-url (concat "mailto:" path))))
       ("news" :follow (lambda (path) (browse-url (concat "news:" path)))) ("shell" :follow org--open-shell-link))
org-agenda-files '("/tmp/org-test/test.org")
org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
)