Please help to review about integration service company (Integrate Wordpress with WHMCS)

Hello,
I'm interesting to use the integration service company for integrate my wordpress theme with WHMCS.
I need help to review and share your experience.
Who's the best service, cover your needs, no hidden condition and reasonable of service fee?
1.hostthebest.com
2.whmcsthemes.com
3.WHMCSintegration.ca
4.Others

Regards,
Thananit