A company front-end with icons.

Differences with the built-in front-end:

• Differents colors for differents backends.
• Icons associated to functions/variables/.. and their backends
• Display candidate's documentation (support quickhelp-string)
• Not limited by the current window size, buffer's text properties, .. (it's better than you might think)

This package requires emacs 26.
Also, not compatible with emacs in a tty.

;; With use-package:
(use-package company-box
  :hook (company-mode . company-box-mode))

;; Or:
(require 'company-box)
(add-hook 'company-mode-hook 'company-box-mode)

To customize:
M-x customize-group [RET] company-box [RET]

See the docstring of the variable company-box-backends-colors:
C-h v company-box-backends-colors

You can select different themes with company-box-icons-alist

See the variable company-box-icons-functions

For now, there are customs icons for 4 backends only: company-lsp, company-elisp, company-yasnippet and company-php.
You can customize their icons with the variables:
company-box-icons-lsp, company-box-icons-elisp, company-box-icons-yasnippet and company-box-icons-acphp.

Notes:
By default, images are used to display icons.
You can also use font icons
With images, you can't change icons colors